Trade accounts and notes receivable, net of allowance for doubtful accounts of 7,455 million yen in 2009 and 8,555 million yen in 2010 (notes 2, 8 and 19) Accounts Trade payables: Income taxes payable (note 10) Accrued expenses (note 12) Less accumulated depreciation and amortization Accumulated other comprehensive income (loss), net (notes 6, 10, 12, 14 and 16) Accumulated other comprehensive income (loss), net Additional Paid in Capital Capital surplus Capital surplus Adjustments to reconcile net income to net cash provided by operating activities: Trade accounts and notes receivable, allowance for doubtful accounts Amendment Flag Total assets Total assets Assets Total current assets Total current assets Current assets: Buildings This element represents movements related to capital transactions between a parent company and consolidated subsidiaries or affiliated companies and other transactions which are not defined in the taxonomy. Capital transactions and others Cash and cash equivalents Cash and cash equivalents at end of year Cash and cash equivalents at beginning of year Net change in cash and cash equivalents Net change in cash and cash equivalents Supplemental Disclosures of Cash Flow Information Amount collected in lease/loan receivables held by our subsidiaries, which carry out financial business such as leasing/loans. Collections of finance subsidiaries-receivables Commitments and contingent liabilities (notes 17 and 18) Commitments and Contingent Liabilities Common stock Common stock, authorized Common stock, issued Common stock, authorized 7,086,000,000 shares; issued 1,834,828,430 shares Total comprehensive income (loss) Total comprehensive income (loss) Comprehensive income (loss) : Accumulated Other Comprehensive Income (Loss) Construction in progress Cost of sales (note 2) Costs and Expenses Costs and Expenses, Total Operating costs and expenses: Current Fiscal Year End Date Current Short-term and Long-term Debt Deferred Deferred income taxes Deferred income taxes (note 10) The expense recognized in the current period that allocates the cost of a tangible and intangible assets excluding properties on operating lease over the assets' useful lives. Depreciation excluding property on operating leases The expense recognized in the current period that allocates the cost of properties on operating lease over the assets' useful lives. Depreciation of property on operating leases Risk Management Activities and Derivative Financial Instruments Disclosure concerning the dividend and the legal reserves, the provisions for the dividend. It includes reserve requirements for capital surplus and retained earnings, the dividend per share paid in this period, the dividend per share decided at the Shareholders Annual General Meeting, and total amount of dividend. Dividends and Legal Reserves Dividends paid to Honda Motor Co., Ltd. shareholders Dividends paid to Honda Motor Co., Ltd. shareholders Document - Document and Entity Information [Abstract] Document - Document and Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date Document Type Basic net income attributable to Honda Motor Co., Ltd. per common share (note 1(o)) Effect of exchange rate changes on cash and cash equivalents Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Current Reporting Status Entity [Domain] Entity Filer Category Entity Registrant Name Entity Well-known Seasoned Issuer Equity Component [Domain] Dividends from affiliates Investments in and Advances to affiliates Fair Value Measurements Short-term lease/loan receivables, net of allowance for credit losses, allowance for losses on lease residual value, and unearned interest income and fees. It includes retained interest in securitized lease/loan receivables. Financial Services Assets Finance Receivables, Net Of Allowance, Current Finance subsidiaries-receivables, net (notes 2, 3, 8 and 19) Long-term lease/loan receivables, net of allowance for credit losses, allowance for losses on lease residual value, and unearned interest income and fees. Financial Services Assets Finance Receivables, Net Of Allowance, Noncurrent Finance subsidiaries-receivables, net (notes 2, 3, 8 and 19) The amount of impairment loss for fixed assets, intangible assets, and goodwill, excluding operating lease assets as the lessor. Impairment loss on long-lived assets and goodwill excluding property on operating leases The amount of impairment loss for operating lease assets as the lessor. Impairment loss on property on operating leases Impairment loss on investments in securities The consolidated profit or loss for the period, net of income taxes, excluding the portion attributable to the noncontrolling interest and the equity in income of affiliates. Income before equity in income of affiliates Income before equity in income of affiliates Income before income taxes and equity in income of affiliates Income before income taxes and equity in income of affiliates Equity in income of affiliates (note 5) Equity in income of affiliates Income Statement [Abstract] Income Taxes Income Tax Expense (Benefit) Income Tax Expense (Benefit), Total Income tax expense (note 10): Trade accounts and notes receivable Trade accounts and notes receivable Trade accounts and notes payable Income taxes payable Accrued expenses Increase (Decrease) in Inventories Inventories Decrease (increase) in assets: Increase (decrease) in liabilities: Increases/decrease in operating assets/liabilities, and adjustments for non-cash items, which are not defined in the taxonomy. Other, net Other, net Other assets Other assets Increase (Decrease) in Other Operating Liabilities Other liabilities The net change in the beginning and end of period Other Current Assets balances. Other current assets Other current assets The net change in the beginning and end of period Other Current Liabilities balances. Other current liabilities Interest Expense Interest expense Inventories Inventories (notes 4 and 8) Interest income Investments in and advances to affiliates (note 5) Investments and Advances-Other Land Legal Entity [Axis] Total liabilities Total liabilities Total liabilities and equity Total liabilities and equity Liabilities and Equity Total current liabilities Total current liabilities Current liabilities: Finance Subsidiaries-Receivables and Securitizations Current portion of long-term debt (notes 3 and 8) Long-term debt, excluding current portion (notes 3 and 8) Total investments and advances Total investments and advances Investments and advances: Machinery and equipment Stockholders' Equity Attributable to Noncontrolling Interest Noncontrolling interests (note 1(c)) Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Dividends paid to noncontrolling interests Net Cash Provided by (Used in) Financing Activities Net cash provided by (used in) financing activities Cash flows from financing activities: Net cash used in investing activities Net cash used in investing activities Cash flows from investing activities: Net cash provided by operating activities Net cash provided by operating activities Cash flows from operating activities (note 13): Net income attributable to Honda Motor Co., Ltd. (note 1(c)) Net income attributable to Honda Motor Co., Ltd. (note 1(c)) Less: Net income attributable to noncontrolling interests (note 1(c)) Noncontrolling interests (note 1(c)) Nonoperating Income (Expense) Nonoperating Income (Expense), Total Other income (expenses): Notes Notes to Financial Statements [Abstract] Notes to Financial Statements [Abstract] Operating income Operating income Leases Property on Operating Leases General and Summary of Significant Accounting Policies Legal reserves (note 11) Legal reserves Other current assets (notes 6, 8 and 16) Other assets (notes 2, 8, 10, 12 and 16) Unrealized gains (losses) on marketable securities, net Pension and other postretirement benefits adjustments Unrealized gains (losses) on derivative instruments, net Adjustments from foreign currency translation Other comprehensive income (loss), net of tax (note 14) Other noncurrent investments not otherwise specified in the taxonomy, including investments in marketable securities. Other, including marketable equity securities (note 6) Other current liabilities (notes 8, 10 and 16) Other Liabilities Disclosure [Text Block] Other Liabilities Other liabilities (notes 9, 10 and 12) Other, net (notes 1(p), 6 and 16) Parent Company [Member] Total Honda Motor Co., Ltd. shareholders' equity Cash reduction resulting from purchases of operating lease assets as the lessor. Purchases of operating lease assets Purchases of operating lease assets Dividends paid (note 11) Dividends paid (note 11) Dividends paid to noncontrolling interests Dividends paid to noncontrolling interests Payments for purchases of available-for-sale securities Payments for purchases of available-for-sale securities Amount of increase in lease/loan receivables held by our subsidiaries, which carry out financial business such as leasing/loans. Acquisitions of finance subsidiaries-receivables Acquisitions of finance subsidiaries-receivables Payments for purchases of held-to-maturity securities Payments for purchases of held-to-maturity securities Increase in investments and advances Increase in investments and advances Capital expenditures Capital expenditures Pension and Other Postretirement Benefits Proceeds from long-term debt Proceeds from redemptions of held-to-maturity securities Increase (decrease) in short-term debt, net Decrease in investments and advances Proceeds from sales of available-for-sale securities Proceeds from sales of property, plant and equipment The amount for transfers of lease/loan receivables held by our subsidiaries, which carry out financial business such as leasing/loans, minus the amount repurchased. Sales (repurchases) of finance subsidiaries-receivables, net Cash income resulting from sales of operating lease assets as the lessor. Proceeds from sales of operating lease assets Net income Net income (note 1(c)) Net income (note 1(c)) Property, Plant and Equipment, Gross Property, Plant and Equipment, Gross, Total Property, plant and equipment, at cost (note 8): Net property, plant and equipment Net property, plant and equipment Less accumulated depreciation Vehicles Net property on operating leases Net property on operating leases Property on operating leases (note 7): Provision for credit and lease residual losses on finance subsidiaries-receivables Selected Quarterly Financial Data (Unaudited) *1 Repayments of Long-term Debt Repayments of long-term debt Research and development Retained earnings (note 11) Retained earnings Net sales and other operating revenue (note 2) Increase/decrease in cash resulting from sale/purchase of treasury stock. Sales (purchases) of treasury stock, net Subsequent Events Allowances for Trade Receivable and Finance Subsidiaries-receivables Variable Interest Entities Segment Information Selling, general and administrative Short-term debt (notes 3 and 8) Statement, Equity Components [Axis] Statement [Line Items] Statement of Cash Flows [Abstract] Statement of Financial Position [Abstract] Statement of Stockholders' Equity [Abstract] Statement [Table] Stockholders' Equity Attributable to Parent Total Honda Motor Co., Ltd. shareholders' equity Honda Motor Co., Ltd. shareholders' equity: Total equity (note 1(c)) Ending Balance Beginning Balance Total equity (note 1(c)) Equity: Transfer to legal reserves Transfer to legal reserves Reissuance of treasury stock Trading Symbol Treasury stock Treasury stock, shares Treasury stock, at cost 20,219,430 shares in 2009 and 20,225,694 shares in 2010 Treasury stock, at cost 20,219,430 shares in 2009 and 20,225,694 shares in 2010 Purchase of treasury stock Purchase of treasury stock Loss (gain) on derivative instruments, net Loss (gain) on derivative instruments, net