Expenses - Schedule of Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Expenses [Abstract]
Insurance	$ 27	$ 31	$ 84	$ 74
Regulatory fees and assessments	24	28	77	65
Securities processing	4	10	20	20
Litigation	3	47	(15)	47
Other	86	71	261	231
Total other expenses	$ 144	$ 187	$ 427	$ 437