Pension and Severance Plans (Accumulated Benefit Obligations for All Defined Benefit Pension Plans) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Japan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	¥ 654,209	¥ 1,029,910
Foreign plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligations	¥ 354,100	¥ 336,185

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant