Preferred Stock - Non-Cumulative Perpetual Preferred Stock (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares Outstanding, preferred (in shares)		26,750
Liquidation Amount		$ 538
Carrying Amount		$ 520	$ 470
Series A
Class of Stock [Line Items]
Annual Dividend Rate		6.20%
Shares Outstanding, preferred (in shares)		0
Liquidation Amount		$ 0
Carrying Amount		$ 0	95
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 B | LIBOR | Beginning on or after August 1, 2025
Class of Stock [Line Items]
Basis spread on variable rate		426.20%
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 C | LIBOR | Beginning on or after May 1, 2026
Class of Stock [Line Items]
Basis spread on variable rate		492.00%
Series D
Class of Stock [Line Items]
Annual Dividend Rate		6.10%
Shares Outstanding, preferred (in shares)		10,000
Liquidation Amount		$ 100
Carrying Amount		$ 94	94
Series D | LIBOR | Beginning on or after May 1, 2024
Class of Stock [Line Items]
Basis spread on variable rate		385.90%
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
Series F
Class of Stock [Line Items]
Annual Dividend Rate	4.70%	4.70%
Shares Outstanding, preferred (in shares)		1,500
Liquidation Amount		$ 150
Carrying Amount	$ 145	$ 145	$ 0