Business Segments Additional Information (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) segment	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	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
Group Reporting Basis Income (loss) from continuing operations before income tax		$ 109	$ 342	342	$ 785
GBM - Portion of Large Corporate Client Group [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Income (loss) from continuing operations before income tax						$ 83	$ 54
Operating Segments [Member] | RBWM [Member]
Segment Reporting Information [Line Items]
Increase to loss before tax			9		25
Group Reporting Basis Income (loss) from continuing operations before income tax		(34)	(13)	(24)	(82)
Operating Segments [Member] | GBM [Member]
Segment Reporting Information [Line Items]
Group Reporting Basis Income (loss) from continuing operations before income tax		$ 70	$ 177	$ 6	$ 377
Scenario, Forecast [Member] | GBM [Member]
Segment Reporting Information [Line Items]
Increase to loans	$ 3,400
Increase in deposits	$ 2,400