Expenses - Schedule of Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Expenses [Abstract]
Insurance	$ 93	$ 126	$ 80
Regulatory fees and assessments	82	115	74
Litigation	50	422	173
Securities processing	42	79	68
Other	317	276	356
Total other expenses	$ 584	$ 1,018	$ 751