Income Taxes (Expiry Schedule of Net Operating Loss Carryforwards) (Detail) ¥ in Millions	Mar. 31, 2022 JPY (¥)
Income Tax Disclosure [Abstract]
2023	¥ 8,346
2024	17,768
2025	20,038
2026	24,902
2027	12,168
Thereafter	145,823
Indefinite period	49,526
Total	¥ 278,571

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319

Name:	us-gaap_OperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant