Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

Deferred compensation awards - Additional information (Detail) - JPY (¥) ¥ / shares in Units, ¥ in Millions			12 Months Ended
	May 25, 2026	May 14, 2026	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2024
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total cash paid to tax authorities			¥ 18,214	¥ 20,583	¥ 12,669
RSU [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Extending vesting period		4 years	7 years
Weighted-average grant date fair value per award			¥ 811	¥ 857	¥ 466
Aggregate value, outstanding			¥ 151,563
Total unrecognized compensation cost, based on fair value			¥ 16,425
Weighted-average period for recognizing unrecognized compensation cost (in years)			1 year 9 months 18 days
Total number of RSU granded		29,736,800
Number shares delivered			43,567,027
Total value of units delivered			¥ 56,928	¥ 63,041	¥ 34,362
Total fair value of awards vested			56,751	62,719	36,607
Total cash paid to tax authorities			¥ 18,214	20,583	12,669
RSU [Member] \| Minimum [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period		1 year	1 year
RSUs allotment date from the date of the disposal decision		4 years
RSU [Member] \| Maximum [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period		3 years	3 years
RSUs allotment date from the date of the disposal decision		7 years
SAR Plan B [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Exercise price per share			¥ 1
Vesting period			3 years
RSU and SAR [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total compensation expense recognized within Non-interest expenses-Compensation and benefits			¥ 40,639	38,381	35,577
NSU and CSU [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total compensation expense recognized within Non-interest expenses-Compensation and benefits			15,583	7,995	15,936
Tax benefits recognized in earnings for compensation expense			1,054	174	186
NSU [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period	4 years
Total unrecognized compensation cost, based on fair value			¥ 2,455
Weighted-average period for recognizing unrecognized compensation cost (in years)			9 months 18 days
Total fair value of awards vested			¥ 14,570	13,249	7,479
Total grant date fair value	¥ 6,000
CSU [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total unrecognized compensation cost, based on fair value			0
Total fair value of awards vested			¥ 1,607	¥ 3,190	¥ 3,179
PSU [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Share based compensation arrangement by share based payment award at percentage payout rate		150.00%
Granted awards		541,000
PSU [Member] \| Maximum [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Granted awards		811,500