Subsequent Events (Details) - USD ($)		1 Months Ended	12 Months Ended
	Jan. 14, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 31, 2015
Subsequent Event [Line Items]
Preferred stock cash dividend			$ 152,000,000	$ 210,000,000	$ 188,000,000
Series F Preferred Stock
Subsequent Event [Line Items]
Preferred stock, shares outstanding (in shares)			7,500
Liquidation preference per share (USD per share)						$ 100,000
Preferred stock cash dividend			$ 47,000,000	$ 40,000,000
Series F Preferred Stock | Subsequent Event
Subsequent Event [Line Items]
Redemption price	$ 500,000,000
Preferred shares to be redeemed (in shares)	5,000
Preferred stock, shares outstanding (in shares)	7,500
Liquidation preference per share (USD per share)	$ 100,000
Preferred stock cash dividend	$ 953.38	$ 7,000,000
Series F Preferred Stock, Depository Share
Subsequent Event [Line Items]
Liquidation preference per share (USD per share)						$ 1,000
Series F Preferred Stock, Depository Share | Subsequent Event
Subsequent Event [Line Items]
Liquidation preference per share (USD per share)	$ 1,000
Preferred stock cash dividend	$ 9.5338