Preferred Stock - Non-Cumulative Perpetual Preferred Stock (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares Outstanding, preferred (in shares)	26,750	26,750
Liquidation Amount	$ 538	$ 538
Carrying Amount	$ 520	$ 520	$ 470
Beginning on or after August 1, 2025 | LIBOR
Class of Stock [Line Items]
Basis spread on variable rate		4.262%
Beginning on or after May 1, 2026 | LIBOR
Class of Stock [Line Items]
Basis spread on variable rate		4.92%
Beginning on or after May 1, 2024 | LIBOR
Class of Stock [Line Items]
Basis spread on variable rate		3.859%
Series A
Class of Stock [Line Items]
Annual Dividend Rate		6.20%
Shares Outstanding, preferred (in shares)	0	0
Liquidation Amount	$ 0	$ 0
Carrying Amount	$ 0	$ 0	95
Series B
Class of Stock [Line Items]
Annual Dividend Rate		6.625%
Shares Outstanding, preferred (in shares)	8,000	8,000
Liquidation Amount	$ 80	$ 80
Carrying Amount	$ 77	$ 77	77
Series C
Class of Stock [Line Items]
Annual Dividend Rate		6.60%
Shares Outstanding, preferred (in shares)	5,750	5,750
Liquidation Amount	$ 58	$ 58
Carrying Amount	$ 59	$ 59	59
Series D
Class of Stock [Line Items]
Annual Dividend Rate		6.10%
Shares Outstanding, preferred (in shares)	10,000	10,000
Liquidation Amount	$ 100	$ 100
Carrying Amount	$ 94	$ 94	94
Series E
Class of Stock [Line Items]
Annual Dividend Rate		6.50%
Shares Outstanding, preferred (in shares)	1,500	1,500
Liquidation Amount	$ 150	$ 150
Carrying Amount	$ 145	$ 145	145
Series F
Class of Stock [Line Items]
Annual Dividend Rate	4.70%	4.70%
Shares Outstanding, preferred (in shares)	1,500	1,500
Liquidation Amount	$ 150	$ 150
Carrying Amount	$ 145	$ 145	$ 0