Employee Benefits - Schedule of expense recognized in Compensation and benefit in the Consolidated Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Contribution Savings Plans
U.S.	$ 142	$ 133	$ 123
U.K.	43	42	42
Other	27	25	30
Expense recognized for defined contribution savings plans	$ 212	$ 200	$ 195