Equity Equity (Preferred Stock Classification) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	$ 999	$ 500
Preferred Stock, Shares Authorized	200,000,000		200,000,000
Preferred Stock, Shares Issued	26,072,200		26,072,200
Preferred Stock, Shares Outstanding	26,072,200		26,072,200
Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	27,600,000		27,600,000
Preferred Stock, Shares Issued	24,000,000		24,000,000
Preferred Stock, Shares Outstanding	24,000,000		24,000,000
Series C Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	1,500,000		1,500,000
Preferred Stock, Shares Issued	500,000		500,000
Preferred Stock, Shares Outstanding	500,000		500,000
Series D Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	500,000		500,000
Preferred Stock, Shares Issued	500,000		500,000
Preferred Stock, Shares Outstanding	500,000		500,000
Series E Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	32,200		32,200
Preferred Stock, Shares Issued	32,200		32,200
Preferred Stock, Shares Outstanding	32,200		32,200
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	40,000		40,000
Preferred Stock, Shares Issued	40,000		40,000
Preferred Stock, Shares Outstanding	40,000		40,000
Series A Junior Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	10,000,000		10,000,000
Preferred Stock, Shares Issued	0		0
Preferred Stock, Shares Outstanding	0		0
Not Designated Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	159,327,800		159,327,800
Preferred Stock, Shares Issued	0		0
Preferred Stock, Shares Outstanding	0		0
Series G Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	1,000,000		1,000,000
Preferred Stock, Shares Issued	1,000,000		1,000,000
Preferred Stock, Shares Outstanding	1,000,000		1,000,000