Preferred Stock - Non-Cumulative Perpetual Preferred Stock (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares Outstanding, preferred (in shares)	26,250
Liquidation Amount	$ 488
Carrying Amount	$ 470	$ 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)	1,000
Liquidation Amount	$ 100
Carrying Amount	$ 96	96
Series B
Class of Stock [Line Items]
Annual Dividend Rate	6.625%
Shares Outstanding, preferred (in shares)	8,000
Liquidation Amount	$ 80
Carrying Amount	$ 77	77
Series C
Class of Stock [Line Items]
Annual Dividend Rate	6.60%
Shares Outstanding, preferred (in shares)	5,750
Liquidation Amount	$ 58
Carrying Amount	$ 59	59
Series D
Class of Stock [Line Items]
Annual Dividend Rate	6.10%
Shares Outstanding, preferred (in shares)	10,000
Liquidation Amount	$ 100
Carrying Amount	$ 93	93
Series E
Class of Stock [Line Items]
Annual Dividend Rate	6.50%
Shares Outstanding, preferred (in shares)	1,500
Liquidation Amount	$ 150
Carrying Amount	$ 145	$ 145