Securitization Activities - Firms Continuing Involvement in Securitization Entities to Which Firm Sold Assets (Parenthetical) (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Transfers and Servicing of Financial Assets [Abstract]
Fair value of retained interests	$ 1,880	$ 1,160

Fair value portion of interest continued to be held by a transferor after transferring financial assets to a third party.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 15
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68074228&loc=d3e94415-111705

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