Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Dividends Payable [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid		$ 17.1875	$ 17.1875
Common Stock, Dividends, Per Share, Cash Paid	[1]	$ 1.20
Dividends, Common Stock, Cash	[1]	$ 504
Dividends, Preferred Stock, Cash		$ 28	$ 28
Common stock repurchased during period, shares		0.4
Purchases of Common Stock		$ (73)		$ (42)
Availability Under ATM		$ 750
Common Stock [Member]
Dividends Payable [Line Items]
Dividends Payable, Date Declared	[1]	Feb. 20, 2020
Dividends Payable, Date of Record	[1]	Mar. 13, 2020
Dividends Payable, Date to be Paid	[1]	Mar. 31, 2020
Preferred Stock [Member]
Dividends Payable [Line Items]
Dividends Payable, Date Declared		Mar. 12, 2020	Dec. 09, 2019
Dividends Payable, Date of Record		Apr. 15, 2020	Jan. 15, 2020
Dividends Payable, Date to be Paid		May 01, 2020	Feb. 03, 2020

[1] Inclusive of dividends accrued for holders of unvested restricted stock units, which will be paid when and if the restricted stock units vest.