Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss)
Balance	$ 1,570	$ 1,399	$ 1,336
Other comprehensive income (loss), net of tax	48	(31)	(9)
Balance	1,788	1,570	1,399
Investment Securities
Accumulated Other Comprehensive Income (Loss)
Balance	(47)	(18)	(8)
Unrealized gain (loss)	57	(30)	(19)
Less: Tax provision (benefit)	14	(7)	(7)
Net unrealized gain (loss)	43	(23)	(12)
Reclassifications out of AOCI	6	(1)	3
Less: Tax provision	1	0	1
Net unrealized gain (loss) reclassified out of AOCI	5	(1)	2
Reclassification of certain income tax effects	0	(5)	0
Other comprehensive income (loss), net of tax	48	(29)	(10)
Balance	1	(47)	(18)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss)
Balance	0	2	1
Unrealized gain (loss)	0	27	5
Less: Tax provision (benefit)	0	7	1
Net unrealized gain (loss)	0	20	4
Reclassifications out of AOCI		(30)	(5)
Less: Tax provision	0	(8)	(2)
Net unrealized gain (loss) reclassified out of AOCI	0	(22)	(3)
Other comprehensive income (loss), net of tax	0	(2)	1
Balance	$ 0	$ 0	$ 2