Gains on Investment Securities and Dividends (Gains on Investment Securities and Dividends) (Detail) - Gains (losses) on investment securities and dividends - JPY (¥) ¥ in Millions	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Net Investment Income [Line Items]
Net gains on investment securities	¥ 44,622	¥ 20,204	¥ 14,273
Dividends income	1,475	2,295	1,685
Total revenues	¥ 46,097	¥ 22,499	¥ 15,958

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details