Business Segments 1 - Group Reporting Basis to US GAAP Adjustments from previous table (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Unquoted Equity Securities [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	$ 0		$ 0		$ 0
Group Reporting Basis Other revenues	0		0		0
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	0		0		0
Group Reporting Basis Income (loss) from continuing operations before income tax	0		0		0
Reclassification of Financial Assets [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	(10)		(14)		(64)
Group Reporting Basis Other revenues	8		40		181
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	0		0		0
Group Reporting Basis Income (loss) from continuing operations before income tax	(2)		26		117
Securities (Assets) [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0		0		0
Group Reporting Basis Other revenues	0		(1)		0
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	(3)		(2)		(12)
Group Reporting Basis Income (loss) from continuing operations before income tax	3		1		12
Derivatives [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0		0		(4)
Group Reporting Basis Other revenues	(4)		(3)		(5)
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	0		0		0
Group Reporting Basis Income (loss) from continuing operations before income tax	(4)		(3)		(9)
Loan Impairment [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	(56)		(57)		(34)
Group Reporting Basis Other revenues	1		1		3
Group Reporting Basis Provision for credit losses	120		(11)		73
Group Reporting Basis Operating expenses	1		1		0
Group Reporting Basis Income (loss) from continuing operations before income tax	(176)		(46)		(104)
Property [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0		0		(9)
Group Reporting Basis Other revenues	0		0		16
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	(16)		(17)		(21)
Group Reporting Basis Income (loss) from continuing operations before income tax	16		17		28
Pension Costs [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0		0		0
Group Reporting Basis Other revenues	0		0		0
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	11		24		11
Group Reporting Basis Income (loss) from continuing operations before income tax	(11)		(24)		(11)
Goodwill [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0
Group Reporting Basis Other revenues	0
Group Reporting Basis Provision for credit losses	0
Group Reporting Basis Operating expenses	0
Group Reporting Basis Income (loss) from continuing operations before income tax	0
Litigation [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0
Group Reporting Basis Other revenues	0
Group Reporting Basis Provision for credit losses	0
Group Reporting Basis Operating expenses	(135)
Group Reporting Basis Income (loss) from continuing operations before income tax	135
Sale of London Branch Precious Metals Business [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0
Group Reporting Basis Other revenues	(98)
Group Reporting Basis Provision for credit losses	0
Group Reporting Basis Operating expenses	0
Group Reporting Basis Income (loss) from continuing operations before income tax	(98)
Sale of Cards and Retail Services Business [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income					0
Group Reporting Basis Other revenues					(92)
Group Reporting Basis Provision for credit losses					0
Group Reporting Basis Operating expenses					0
Group Reporting Basis Income (loss) from continuing operations before income tax					(92)
Goodwill Impairment [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income			0
Group Reporting Basis Other revenues			0
Group Reporting Basis Provision for credit losses			0
Group Reporting Basis Operating expenses			135
Group Reporting Basis Income (loss) from continuing operations before income tax			(135)
Low Income Housing Tax Credit [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	0		0		0
Group Reporting Basis Other revenues	(16)		(30)		(29)
Group Reporting Basis Provision for credit losses	0		0		0
Group Reporting Basis Operating expenses	0		0		0
Group Reporting Basis Income (loss) from continuing operations before income tax	(16)		(30)		(29)
Other [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	(8)		(5)		(12)
Group Reporting Basis Other revenues	(23)		15		(31)
Group Reporting Basis Provision for credit losses	(40)		11		0
Group Reporting Basis Operating expenses	(16)		60		(14)
Group Reporting Basis Income (loss) from continuing operations before income tax	25		(61)		(29)
Group Reporting Basis Adjustments [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Net interest income	(74)	[1]	(76)	[1]	(123)	[1]
Group Reporting Basis Other revenues	(132)		22		43
Group Reporting Basis Provision for credit losses	80		0		73
Group Reporting Basis Operating expenses	(158)	[2]	201	[2]	(36)	[2]
Group Reporting Basis Income (loss) from continuing operations before income tax	(128)		(255)		(117)
Group Reporting Basis Total assets	(54,138)		(49,879)		(67,543)
Group Reporting Basis Adjustments [Member] | Unquoted Equity Securities [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	(195)		(163)		(108)
Group Reporting Basis Adjustments [Member] | Reclassification of Financial Assets [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	11		11		(4)
Group Reporting Basis Adjustments [Member] | Securities (Assets) [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	(13)		(24)		(27)
Group Reporting Basis Adjustments [Member] | Derivatives [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	(53,973)		(49,876)		(67,762)
Group Reporting Basis Adjustments [Member] | Loan Impairment [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	(204)		(94)		(66)
Group Reporting Basis Adjustments [Member] | Property [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	28		37		42
Group Reporting Basis Adjustments [Member] | Pension Costs [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	(166)		(154)		(137)
Group Reporting Basis Adjustments [Member] | Goodwill [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	348
Group Reporting Basis Adjustments [Member] | Litigation [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	1
Group Reporting Basis Adjustments [Member] | Sale of London Branch Precious Metals Business [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	0
Group Reporting Basis Adjustments [Member] | Sale of Cards and Retail Services Business [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets					0
Group Reporting Basis Adjustments [Member] | Goodwill Impairment [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets			348
Group Reporting Basis Adjustments [Member] | Low Income Housing Tax Credit [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	0		0		0
Group Reporting Basis Adjustments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Total assets	$ 25		$ 36		$ 519

[1] Net interest income of each segment represents the difference between actual interest earned on assets and interest paid on liabilities of the segment adjusted for a funding charge or credit. Segments are charged a cost to fund assets (e.g. customer loans) and receive a funding credit for funds provided (e.g. customer deposits) based on equivalent market rates. The objective of these charges/credits is to transfer interest rate risk from the segments to one centralized unit in Balance Sheet Management and more appropriately reflect the profitability of segments.

[2] Expenses for the segments include fully apportioned corporate overhead expenses.