Shareholders' Equity - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Class of Stock [Line Items]
Common stock dividends	$ 400
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends paid		$ 29	$ 29
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends paid		$ 16	$ 17