Business Segments Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	4
Maximum annual revenue of small business clients to be served by RBWM	$ 3
Profit before tax	294	$ 755	$ 426
Financing receivable collectively evaluated for impairment, difference in estimate between US GAAP and group reporting basis			174
Increase to provision for credit losses due to review of loss reporting experience	$ (24)	28
Term of lease	10 years
GBM - Portion of Large Corporate Client Group [Member]
Segment Reporting Information [Line Items]
Profit before tax		83	53
GBM [Member]
Segment Reporting Information [Line Items]
Increase to loans		4,800	3,800
Increase in deposits		2,800	1,100
Operating Segments [Member] | RBWM [Member]
Segment Reporting Information [Line Items]
Increase to loss before tax		33	48
Profit before tax	$ (27)	(121)	(86)
Operating Segments [Member] | GBM [Member]
Segment Reporting Information [Line Items]
Profit before tax	$ 175	$ 518	$ 91