v3.26.1
Parent Company Only Condensed Financial Information - Condensed Statements of Cash Flows (Detail) - JPY (¥)
¥ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Cash flows from operating activities:      
Net Income (Loss) ¥ 362,129 ¥ 340,736 ¥ 165,863
Net cash provided by (used in) operating activities (842,960) (678,611) 132,640
Cash flows from investing activities:      
Payments for purchases of office buildings, land, equipment and facilities (353,818) (189,971) (145,784)
Net change in other investing activities (20,015) 16,154 914
Net cash used in investing activities (1,498,923) (848,647) (887,938)
Cash flows from financing activities:      
Proceeds from issuances of long-term borrowings 4,611,984 4,334,376 3,064,698
Payments for repurchases or maturity of long-term borrowings (3,174,186) (3,313,452) (2,101,758)
Payments for repurchases of common stock (101,499) (59,006) (61,029)
Payments for cash dividends (179,742) (112,541) (60,164)
Net cash provided by financing activities 2,095,851 1,679,697 1,012,850
Net increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents (106,719) 126,419 478,170
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year 4,425,441 4,299,022 3,820,852
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of year 4,318,722 4,425,441 4,299,022
Parent Company [Member]      
Cash flows from operating activities:      
Net Income (Loss) 362,129 340,736 165,863
Total equity in undistributed earnings of subsidiaries (147,125) (156,127) (36,166)
Adjustments and other 115,481 24,323 57,205
Net cash provided by (used in) operating activities 330,485 208,932 186,902
Cash flows from investing activities:      
Payments for purchases of office buildings, land, equipment and facilities (59,045) (29,375) (32,525)
Payments for issuance of loans to subsidiaries (1,793,469) (2,756,195) (1,368,396)
Proceeds from repayment of loans to subsidiaries 1,190,050 2,144,444 710,251
Increase in investments in subsidiaries (109,174) (10,342) (32,394)
Decrease in investments in subsidiaries 31,247 11,203 64,389
Net change in other investing activities 5,477 4,510 23,773
Net cash used in investing activities (734,914) (635,755) (634,902)
Cash flows from financing activities:      
Proceeds from issuances of long-term borrowings 965,501 350,753 308,506
Payments for repurchases or maturity of long-term borrowings (784,416) (1,153,652) (577,336)
Proceeds from issuances of long-term borrowings from subsidiaries 272,036 775,053 371,450
Repayments of senior debt (240,738) (11,563)
Proceeds from issuances of short-term borrowings from subsidiaries 3,322,600 2,385,000 539,863
Payments for repurchases or maturity of short-term borrowings from subsidiaries (2,800,000) (1,820,902)
Payments for repurchases of common stock (101,499) (59,006) (61,029)
Payments for cash dividends (179,742) (112,541) (60,164)
Net change in other financing activities (17,792) (19,170) (11,718)
Net cash provided by financing activities 435,950 345,535 498,009
Net increase (decrease) in cash, cash equivalents, restricted cash and restricted cash equivalents 31,521 (81,288) 50,009
Cash, cash equivalents, restricted cash and restricted cash equivalents at beginning of year 149,626 230,914 180,905
Cash, cash equivalents, restricted cash and restricted cash equivalents at end of year ¥ 181,147 ¥ 149,626 ¥ 230,914