RELATED PARTY TRANSACTIONS AND SIGNIFICANT TRANSACTIONS WITH RBS - Schedule of Related Party Fee Impact on Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Related Party Fees Effect on Income [Line Items]
The effect of related party service fees on outside services	$ 371	$ 420	$ 360
RBSG
Schedule of Related Party Fees Effect on Income [Line Items]
The effect of related party service and referral fees, net of occupancy expense, on total fee income	10	16	26
The effect of related party service fees on outside services	$ 11	$ 22	$ 20

A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07.2(a),(b),(c),(d))
-URI http://asc.fasb.org/extlink&oid=6488393&loc=d3e606610-122999

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 225
-Section 45
-Paragraph 3
-Subparagraph (k)
-URI http://asc.fasb.org/extlink&oid=6488370&loc=d3e13550-115849

Name:	us-gaap_ProfessionalFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration