Fair Value (Fair Values of Financial Instruments and Methods and Assumptions Used to Estimate Fair Value) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2016	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Aggregated carrying amounts of estimate not practicable investments	¥ 13,514	¥ 13,651

This item represents a financial instrument (as defined) for which it is not practicable to estimate fair value. Such disclosure may be for an individual financial instrument or a class of financial instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=29638263&loc=d3e39828-111592

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