Deposits - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Banking and Thrift [Abstract]
Time deposits, including certificates of deposit issued in amounts of 10 million Yen or more	¥ 1,064,398	¥ 952,970

Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher SEC
-Name Industry Guide
-Number 3
-Section V
-Paragraph D-E