Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated other comprehensive income (loss)
Beginning balance	$ 2,498	$ 1,971	$ 2,201	$ 1,788
Other comprehensive income, net of tax	(7)	0	(9)	45
Ending balance	2,645	2,195	2,645	2,195
Investment Securities
Accumulated other comprehensive income (loss)
Beginning balance	35	56	52	1
Unrealized gain (loss)	(11)	0	(33)	72
Less: Tax provision (benefit)	(3)	0	(8)	17
Net unrealized gain (loss)	(8)	0	(25)	55
Other comprehensive income, net of tax	(8)	0	(25)	55
Ending balance	27	56	27	56
Cash Flow Hedges
Accumulated other comprehensive income (loss)
Beginning balance	10	(10)	(5)	0
Unrealized gain (loss)	2	0	19	(13)
Less: Tax provision (benefit)	1	0	5	(3)
Net unrealized gain (loss)	1	0	14	(10)
Reclassifications out of AOCI	1	0	3	0
Less: Tax provision (benefit)	1	0	1	0
Other comprehensive income, net of tax	1	0	16	(10)
Ending balance	$ 11	$ (10)	$ 11	$ (10)