Expenses - Schedule of Expenses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Expenses [Abstract]
Insurance	$ 32	$ 28	$ 64	$ 58
Regulatory fees and assessments	29	18	59	45
Sales advertising public relations	29	15	55	28
Bank operations	22	19	39	34
Litigation	5	(17)	7	(17)
Other	89	69	183	135
Total other expenses	$ 206	$ 132	$ 407	$ 283