Equity Equity (Preferred Stock Dividends) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Dividends Payable [Line Items]
Dividends, Preferred Stock, Cash	$ 68	$ 32
Series A Preferred Stock
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 0.250	$ 0.253
Dividends, Preferred Stock, Cash	$ 6	$ 6
Series C Preferred Stock
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 9.479	$ 0
Dividends, Preferred Stock, Cash	$ 5	$ 0
Series D Preferred Stock
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 29.375	$ 29.375
Dividends, Preferred Stock, Cash	$ 15	$ 15
Series E Preferred Stock
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 351.563	$ 351.563
Dividends, Preferred Stock, Cash	$ 11	$ 11
Series G Preferred Stock
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 19.785	$ 0
Dividends, Preferred Stock, Cash	$ 19	$ 0
Series F Preferred Stock [Member]
Dividends Payable [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 296.875	$ 0
Dividends, Preferred Stock, Cash	$ 12	$ 0