Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated other comprehensive income (loss)
Beginning balance			$ 1,788	$ 1,570
Other comprehensive income, net of tax	$ 0	$ 13	45	52
Ending balance	2,195	1,734	2,195	1,734
Investment Securities
Accumulated other comprehensive income (loss)
Beginning balance	56	(8)	1	(47)
Unrealized gain (loss)	0	18	72	61
Less: Tax provision (benefit)	0	5	17	15
Net unrealized gain (loss)	0	13	55	46
Reclassifications out of AOCI	0	0	0	7
Less: Tax provision	0	0	0	1
Net unrealized gain reclassified out of AOCI	0	0	0	6
Other comprehensive income, net of tax	0	13	55	52
Ending balance	56	5	56	5
Cash Flow Hedges
Accumulated other comprehensive income (loss)
Beginning balance	(10)	0	0	0
Unrealized gain (loss)	0	0	(13)	0
Less: Tax provision (benefit)	0	0	(3)	0
Net unrealized gain (loss)	0	0	(10)	0
Reclassifications out of AOCI	0	0	0	0
Other comprehensive income, net of tax	0	0	(10)	0
Ending balance	$ (10)	$ 0	$ (10)	$ 0