Business Segments - Reconciliation of Group Reporting Basis Segment Results (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Line Items]
Net Interest Income										$ (134)		$ (254)	$ (643)
US GAAP based Net interest income										703		868	1,068
US GAAP based Other operating income (Total other revenues)		$ 93	$ (98)	$ 138	$ (42)	$ (72)	$ 169	$ 47	$ 82	91		226	881
US GAAP based Total operating income (loss)										794		1,094	1,949
US GAAP based Loan impairment charges (Provision for credit losses)		13	18	192	27	(127)	(43)	(197)	2	250	[1]	(365)	(21)
US GAAP Net interest income and other operating income less provision for credit losses										544		1,459	1,970
Operating expenses										185		(398)	(732)
US GAAP based Operating expenses		507	232	522	148	176	174	121	217	1,409		688	932
Profit (loss) before tax										(274)		193	988
Income (loss) from continuing operations before income tax		(258)	$ (166)	$ (408)	$ (33)	80	$ 248	$ 348	$ 95	(865)		771	1,038
US GAAP based Depreciation and amortization										7		9	8
US GAAP based Expenditures for long-lived assets										0		0	6
US GAAP based Customer loans (Receivables)		9,156				22,670				9,156		22,670	26,584
Total Assets		(1,336)				(1,069)				(1,336)		(1,069)	(1,796)
US GAAP based Assets		24,132				31,897				24,132		31,897	37,707
Group Reporting Basis Consolidated Totals [Member]
Segment Reporting [Line Items]
Net Interest Income										1,018		1,376	2,031
Group Reporting Basis Other operating income (Total other revenues)										(192)		(65)	(413)
Group Reporting Basis Total operating income (loss)										826		1,311	1,618
Group Reporting Basis Loan impairment charges (Provision for credit losses)										65		33	711
Group Reporting Basis Net interest income and other operating income less loan impairment charges										761		1,278	907
Operating expenses										1,352		700	857
Profit (loss) before tax										(591)		578	50
Group Reporting Basis Depreciation and amortization										6		9	5
Group Reporting Basis Expenditures for long-lived assets										0		0	6
Group Reporting Basis Customer loans (Receivables)		18,518				23,554				18,518		23,554	29,262
Total Assets		25,468				32,966				25,468		32,966	39,503
Group Reporting Basis Adjustments [Member]
Segment Reporting [Line Items]
Net Interest Income	[2]									(134)		(254)	(643)
Group Reporting Basis Other operating income (Total other revenues)	[2]									97		54	966
Group Reporting Basis Total operating income (loss)	[2]									(37)		(200)	323
Group Reporting Basis Loan impairment charges (Provision for credit losses)	[2]									185		(398)	(732)
Group Reporting Basis Net interest income and other operating income less loan impairment charges	[2]									(222)		198	1,055
Operating expenses	[2]									52		5	67
Profit (loss) before tax	[2]									(274)		193	988
Group Reporting Basis Depreciation and amortization										0	[2]	(1)	2	[2]
Group Reporting Basis Expenditures for long-lived assets										0	[2]	0	0	[2]
Group Reporting Basis Customer loans (Receivables)	[2]	(9,339)				(853)				(9,339)		(853)	(2,644)
Total Assets	[2]	(1,336)				(1,069)				(1,336)		(1,069)	(1,796)
Group Reporting Basis Reclassifications [Member]
Segment Reporting [Line Items]
Net Interest Income	[3]									(181)		(254)	(320)
Group Reporting Basis Other operating income (Total other revenues)	[3]									186		237	328
Group Reporting Basis Total operating income (loss)	[3]									5		(17)	8
Group Reporting Basis Loan impairment charges (Provision for credit losses)	[3]									0		0	0
Group Reporting Basis Net interest income and other operating income less loan impairment charges	[3]									5		(17)	8
Operating expenses	[3]									5		(17)	8
Profit (loss) before tax	[3]									0		0	0
Group Reporting Basis Depreciation and amortization	[3]									1		1	1
Group Reporting Basis Expenditures for long-lived assets	[3]									0		0	0
Group Reporting Basis Customer loans (Receivables)	[3]	(23)				(31)				(23)		(31)	(34)
Total Assets	[3]	$ 0				$ 0				$ 0		$ 0	$ 0

[1] The provision for credit losses and charge-offs for real estate secured receivables during the year ended December 31, 2015 includes $234 million related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. See Note 7, "Receivables Held for Sale," for additional information. The provision for credit losses for real estate secured receivables during the year ended December 31, 2015 was impacted by a release of approximately $19 million associated with an out of period adjustment to our credit loss reserve calculation for a segment of our portfolio.

[2] Group Reporting Basis Adjustments which have been described more fully above, consist of the following:

[3] Represents differences in balance sheet and income statement presentation between U.S. GAAP and the Group Reporting Basis.