Accounting Policies [Abstract] Accounting Policies [Abstract] Accounting Standards Update 2016-01 [Member] ASU 2016-01 Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Receivable Type [Axis] Receivable Type [Axis] Billing Status, Type [Axis] Billing Status, Type [Axis] Accounts Payable Purchase of Property Plant And Equipment Accounts Payable Purchase of Property Plant And Equipment Payable for purchases of property and equipment Accounts receivable balance due. Accounts Receivable Balance Due Account receivable balance due Accounts Receivable, Net, Current Accounts receivable, net of allowance for doubtful accounts Accounts receivable, net of allowance for doubtful accounts of nil as of December 31, 2017 and December 31, 2018 Accrued Income Taxes, Current Income tax payable The total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, such as accrued salaries and bonuses, payroll taxes and fringe benefits. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Accrued Liabilities And Employee Related Liabilities, Current Accrued payroll and welfare expenses Accrued Liabilities, Current Accrued expenses Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated depreciation Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income AOCI Attributable to Parent [Member] Accumulated other comprehensive (loss)/income Additional Paid in Capital, Common Stock Additional paid-in capital Additional Paid-in Capital [Member] Additional Paid-in Capital Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Share-based compensation Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustment to reconcile net income to net cash provided by operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Retained Earnings by Termination of Redeemable Non Controlling Interest of Subsidiary. Adjustments to Retained Earnings by Termination of Redeemable Non Controlling Interest of Subsidiary Termination of redeemable non-controlling interest of a subsidiary (Note 13) Adoption of ASU Consolidation. Adoption Of ASU Consolidation Policy [Policy Text Block] Consolidation Policy Upon Adoption of ASU No. 2015-02 and 2016-17 Advances to vendors. Advances to Vendors Advance to vendors After Modification [Member] After Modification [Member] After Modification Airline and railway ticket. Airline and Railway Ticket [Member] Airline and Railway Ticket [Member] Allowance for Doubtful Accounts Receivable, Current Accounts receivable, allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Reversals Allowance for Doubtful Accounts Receivable, Reversals Reversal of allowance provided Allowance for loan losses, percentage. Allowance for Loan Losses, Percentage Loan loss provision rate Allowance For Loan Losses Roll forward [Table Text Block] Allowance For Loan Losses Roll forward [Table Text Block] Activity in Allowance for Loan Losses Allowance for Notes, Loans and Financing Receivable, Current Loan receivables, allowance for loan losses Allowance for loan losses Amendment Flag Amendment Flag American Depositary Share [Member] American Depositary Share [Member] American Depositary Share American Depositary Shares [Member] American Depositary Shares [Member] American Depositary Shares American Depository Shares to Shares Ratio American Depository Shares to Shares Ratio Number of ADS that each ordinary share represents Amortization of Unearned Income for Financial Lease. Amortization of Unearned Income for Financial Lease Amortization of unearned income for financial leases Amount Due From Related Parties [Member] Amount Due From Related Parties [Member] Amount due from related parties Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries Restricted net assets Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per share Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Asset Management Industry [Member] Asset Management Industry [Member] Asset Management Business Assets Total Assets Assets [Abstract] Assets Assets and Liabilities Eliminated upon Consolidation [Abstract] Assets and Liabilities Eliminated upon Consolidation [Abstract] Assets and Liabilities Eliminated upon Consolidation [Abstract] Assets, Current Total current assets Assets, Current [Abstract] Current assets Current assets: Assets, Fair Value Disclosure Assets reported at fair value on a non-recurring basis Assets, Total [Member] Total Assets Available For Sale Investments Available For Sale Investments Available for sale investments Available-for-sale Securities Available-for-sale investments in debt securities Available-for-sale Securities, Amortized Cost Basis Amortized cost of the available-for-sale investments Available-for-sale Securities, Current Available for sale investments Available-for-sale Securities, Noncurrent Available-for-sale investments Available-for-sale investments in debt securities Award Type [Axis] Award Type [Axis] Basis of Accounting, Policy [Policy Text Block] Basis of Presentation Before Modification [Member] Before Modification [Member] Before Modification Beijing Sequoia Mingde Equity Investment Center Limited Partnership [Member] Beijing Sequoia Mingde Equity Investment Center Limited Partnership [Member] Beijing Sequoia Mingde Equity Investment Center (Limited Partnership) Building [Member] Building Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Percentage of Voting Interests Acquired Equity interest sold to Shanghai Noah Financial Service Percentage of equity shares Business acquisition, percentage of voting interests acquired Equity interest sold to Shanghai Noah Financial Service Business Combination, Consideration Transferred Business acquisition agreement price Purchase price Business Tax And Surcharges Rate Business Tax And Surcharges Rate Business tax and related surcharges Business Tax, Policy Business Tax, Policy [Policy Text Block] Business Tax and Related Surcharges Capital Expenditures Incurred but Not yet Paid Purchase of property and equipment in accounts payable Capitalized Computer Software, Gross Software Carrying Amount and Maximum Exposure to Loss for Equity Method Investments [Table Text Block] Carrying Amount and Maximum Exposure to Loss for Equity Method Investments [Table Text Block] Summary of Maximum Exposure to Loss Associated with Identified Nonconsolidated VIEs Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Cash and cash equivalent Cash and cash equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash and cash equivalents-end of year Cash and cash equivalents-beginning of year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] Reconciliation to amounts on consolidated balance sheets: Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Net increase in cash and cash equivalents Net increases (decrease) in cash, cash equivalents and restricted cash Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Supplemental disclosure of non-cash investing and financing activities: Change in noncontrolling interests. Change in Noncontrolling Interest Non-controlling Interest capital injection Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Class of Stock [Domain] Class of Stock [Domain] Class of Treasury Stock [Table] Class of Treasury Stock [Table] CHINA Mainland of China Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] Commitments and Contingencies Commitments and Contingencies (Note 20) Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Common Class A [Member] Class A Common Class B [Member] Class B Common Stock [Member] Common Stock Common Stock, Par or Stated Value Per Share Ordinary shares, par value Common Stock, Shares Authorized Ordinary shares, shares authorized Common Stock, Shares, Issued Ordinary shares, shares issued Common Stock, Shares, Outstanding Ordinary shares, shares outstanding Common Stock, Value, Issued Ordinary shares Compensation and Employee Benefit Plans [Text Block] Employee Benefit Plans Retirement Benefits [Abstract] Retirement Benefits [Abstract] Compensation Related Costs, Policy [Policy Text Block] Compensation and Benefits Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income attributable to Noah Holdings Limited shareholders Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Less: comprehensive loss attributable to non-controlling interest Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive income Comprehensive Income, Policy [Policy Text Block] Comprehensive Income Computation of Earnings Per Share [Line Items] Computation of Earnings Per Share [Line Items] Computation of Earnings Per Share [Line Items] Computer Software, Intangible Asset [Member] Software Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Concentration Risk, Credit Risk, Policy [Policy Text Block] Concentration of Credit Risk Concentration Risk, Percentage Concentration risk percentage Concentration Risk Type [Domain] Concentration Risk Type [Domain] Condensed Financial Information Disclosure [Abstract] Condensed Financial Information Disclosure [Abstract] Condensed Financial Information of Parent Company Only Disclosure [Text Block] Additional Financial Information of Parent Company - Financial Statements Schedule I Condensed Financial Information of Subsidiaries Disclosure [Abstract] Condensed Financial Information of Subsidiaries Disclosure [Abstract] Condensed Financial Information of Subsidiaries Disclosure [Abstract] Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Comprehensive Income [Table] Condensed Statement of Income Captions [Line Items] Condensed Statement of Income Captions [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Consolidated fund. Consolidated Fund [Member] Consolidated Fund Consolidated Investment Funds Consolidated Investment Funds Number of consolidated investment funds Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net Change from net income attributable to Noah and transfers from non-controlling interest Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net [Abstract] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net [Abstract] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Net [Abstract] Transfers from (to) the non-controlling interest: Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Sale of Interest by Parent Changes in equity ownership on partial disposal of subsidiaries Increase (decrease) in Noah's equity by partial disposal (acquisition) of subsidiaries Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Table Text Block] Summary of Effects of Changes in Group's Ownership Interest in Less than Wholly Owned Subsidiaries on Equity Attributable to Noah Holdings Limited Shareholders Consolidation, Policy [Policy Text Block] Principles of Consolidation Construction in Progress, Gross Construction in progress Contracts Expiration Month and Year Contracts Expiration Month and Year Interest-free loans agreements expiry date Contract termination settlement amount. Contract Termination Settlement Amount Contract termmination settlement amount Contract with Customer, Refund Liability, Current Advance from customers Conversion of Stock, Amount Converted Conversion of convertible notes Convertible Debt, Fair Value Disclosures Convertible note, fair value Convertible Debt [Member] Convertible notes (Notes) Convertible Notes Payable, Noncurrent Convertible notes Convertible Notes Payable, Current Convertible notes Cost Method Investments Long-term investment - cost method investment, Carrying Value Cost Method Investments, Fair Value Disclosure Long-term investment - cost method investment, Fair Value Costs and Expenses Total operating cost and expenses Total operating cost and expenses Total operating cost and expenses Costs and Expenses [Abstract] Operating cost and expenses Operating cost and expenses: Counterparty Name [Axis] Counterparty Name [Axis] Credit Concentration Risk [Member] Credit Concentration Risk Cumulative Effect of New Accounting Principle in Period of Adoption Cumulative effect of adjustment from other comprehensive income to retained earnings Current Fiscal Year End Date Current Fiscal Year End Date Current Income Tax Expense (Benefit) Current Tax Debt Conversion Description [Axis] Debt Conversion Description [Axis] Debt Conversion, Converted Instrument, Amount Portion of debt to be converted Debt Conversion, Name [Domain] Debt Conversion, Name [Domain] Debt Conversion, Original Debt, Amount Amount of convertible notes converted Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Text Block] Convertible Notes Debt Instrument, Convertible, Conversion Price Debt instrument, initial conversion price Debt Instrument, Convertible, Conversion Ratio Debt Instrument, initial conversion rate Debt Instrument, Face Amount Debt instrument, face amount Debt Instrument, Frequency of Periodic Payment Debt Instrument, frequency of periodic payment Debt Instrument, Interest Rate, Stated Percentage Debt instrument, interest rate Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument, Maturity Date Debt instrument, maturity date Debt Instrument Repurchase Price Percentage Of Principal Amount Debt Instrument Repurchase Price Percentage Of Principal Amount Debt Instrument, repurchase price as a percentage of principal amount Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Securities [Member] Debt Securities of Certain Real Estate Funds Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Debt Issuance Costs, Net Debt issuance costs Deferred Income Tax Expense (Benefit) Deferred Tax Deferred Tax Liabilities, Gross Net deferred tax liabilities (after offsetting) Deferred Revenue Deferred revenue from related parties Deferred Revenue, by Arrangement, Disclosure [Table Text Block] Deferred Revenues Related to Recurring Management Fee Received in Advance from Related Parties Deferred Revenue, Current Deferred revenue Deferred revenues Deferred Revenue Disclosure [Abstract] Deferred Revenue Disclosure [Abstract] Deferred Revenue, Revenue Recognized Deferred revenue beginning balance Deferred Tax Assets, Gross Gross deferred tax assets Deferred Tax Assets, Gross [Abstract] Deferred tax assets: Deferred Tax Assets, Net of Valuation Allowance Net deferred tax assets Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Deferred tax assets Non-current deferred tax assets Deferred Tax Assets, Operating Loss Carryforwards Tax loss carry forward Deferred Tax Assets, Other Others Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals Accrued expenses Deferred Tax Assets, Unrealized Losses on Trading Securities Unrealized other income Deferred Tax Assets, Valuation Allowance Deferred tax asset allowance Valuation allowance Deferred Tax Liabilities, Gross [Abstract] Deferred tax liabilities: Deferred Tax Liabilities, Net, Noncurrent Deferred tax liabilities Deferred Tax Liabilities, Unrealized Gains on Trading Securities Unrealized investment income Defined Benefit Plan, Plan Assets, Contributions by Employer Contribution for multi-employer defined contribution plan Deposits for lending service. Deposits for Lending Service Deposits for lending service Deposits from other financial service business. Deposits From Other Financial Service Business Deposits from other financial service business Depreciation Depreciation expense Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Direct Financing Lease, Lease Receivable Long-term receivables from financial leasing service Disaggregation of Revenue [Abstract] Disaggregation of Revenue [Abstract] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table Text Block] Schedule of Disaggregation of Revenue Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Share-Based Compensation Dividend Withholding Tax Rate Dividend Withholding Tax Rate Withholding income tax rate Document And Entity Information [Abstract] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Line Items] Document Information [Line Items] Document Information [Table] Document Information [Table]