Stockholders' Equity (Preferred Stock Issued and Outstanding) (Details) - USD ($) $ / shares in Thousands, $ in Millions			12 Months Ended
	Dec. 11, 2020	Apr. 30, 2020	Dec. 31, 2021	Mar. 30, 2021	Mar. 18, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares issued (in shares)			1,834,000			1,811,000
Shares outstanding (in shares)			1,834,000			1,811,000
Carrying value			$ 9,954			$ 7,733
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			0			600,000
Shares outstanding (in shares)			0			600,000
Liquidation preference (USD per share)			$ 1
Carrying value			$ 0			$ 585
Dividend rate in effect			0.00%
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			750,000			750,000
Shares outstanding (in shares)			750,000			750,000
Liquidation preference (USD per share)			$ 1
Carrying value			$ 728			$ 728
Dividend rate in effect			5.95%
Series J Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			600,000			0
Shares outstanding (in shares)			600,000			0
Liquidation preference (USD per share)			$ 1	$ 1
Carrying value			$ 584			$ 0
Dividend rate in effect			4.45%
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			400,000			400,000
Shares outstanding (in shares)			400,000			400,000
Liquidation preference (USD per share)			$ 1
Carrying value			$ 397			$ 397
Dividend rate in effect			7.00%
Series A Preferred Stock [Member] | LIBOR [Member]
Class of Stock [Line Items]
Floating annual rate			4.82%
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			6,000			6,000
Shares outstanding (in shares)			6,000			6,000
Liquidation preference (USD per share)			$ 100
Carrying value			$ 591			$ 591
Dividend rate in effect			4.625%
Series E Preferred Stock [Member] | LIBOR [Member]
Class of Stock [Line Items]
Floating annual rate			3.315%
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			5,000			5,000
Shares outstanding (in shares)			5,000			5,000
Liquidation preference (USD per share)			$ 100
Carrying value			$ 492			$ 492
Dividend rate in effect			5.00%
Series F Preferred Stock [Member] | LIBOR [Member]
Class of Stock [Line Items]
Floating annual rate			2.575%
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			25,000			25,000
Shares outstanding (in shares)			25,000			25,000
Liquidation preference (USD per share)		$ 100	$ 100
Carrying value			$ 2,470			$ 2,470
Dividend rate in effect		5.375%	5.375%
Dividend term			5 years
Series G Preferred Stock [Member] | US Treasury (UST) Interest Rate [Member]
Class of Stock [Line Items]
Dividend term			5 years
Floating annual rate			4.971%
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			25,000			25,000
Shares outstanding (in shares)			25,000			25,000
Liquidation preference (USD per share)	$ 100		$ 100
Carrying value			$ 2,470			$ 2,470
Dividend rate in effect	4.00%		4.00%
Dividend term			10 years
Series H Preferred Stock [Member] | US Treasury (UST) Interest Rate [Member]
Class of Stock [Line Items]
Dividend term			10 years
Floating annual rate			3.079%
Series I Preferred Stock [Member]
Class of Stock [Line Items]
Shares issued (in shares)			23,000			0
Shares outstanding (in shares)			23,000			0
Liquidation preference (USD per share)			$ 100		$ 100
Carrying value			$ 2,222			$ 0
Dividend rate in effect			4.00%
Dividend term			5 years
Series I Preferred Stock [Member] | US Treasury (UST) Interest Rate [Member]
Class of Stock [Line Items]
Dividend term			5 years
Floating annual rate			3.168%
Maturity period			5 years