Income Taxes (Reconciliations of Differences between Tax Provision Computed at Statutory Rate and Consolidated Provision for Income Taxes) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income before income taxes	¥ 504,876	¥ 287,561	¥ 412,561
Tax provision computed at the statutory rate	159,036	90,582	129,957
Increases (reductions) in taxes due to:
Change in valuation allowance	11,464	6,808	2,505
Nondeductible expenses	4,066	2,751	4,319
Nontaxable income	(2,611)	(1,629)	(3,612)
Effect of lower tax rates on certain subsidiaries	(16,584)	(12,895)	(24,862)
Effect of investor taxes on earnings of subsidiaries	8,155	4,590	3,039
Effect of the tax law and rate changes	(142)	1,158	(6,642)
Effect of sale or liquidation of subsidiaries	25,642	878	307
Other, net	(1,762)	(1,496)	826
Provision for income taxes	¥ 187,264	¥ 90,747	¥ 105,837

Income Tax Reconciliation Increases Decreases [Abstract]

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Income tax reconciliation investor taxes on earnings of subsidiary.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets.

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