Business Segments Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of Reportable Segments | segment	4
Maximum annual revenue of small business clients to be served by RBWM	$ 3
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	$ 28