Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
	Oct. 24, 2019	Sep. 30, 2019	Sep. 30, 2018
Class of Stock [Line Items]
Cash set aside to pay dividends		$ 2,760
Subsequent Event [Member]
Class of Stock [Line Items]
Common stock dividends	$ 400
Dividend Declared [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Cash set aside to pay dividends	45
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends paid		58	$ 59
Series A Preferred Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Preferred stock dividends paid	$ 29
Preferred stock dividends declared (in usd per share)	$ 28.75
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividends paid		$ 33
Series B Preferred Stock [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Preferred stock dividends paid	$ 16
Preferred stock dividends declared (in usd per share)	$ 32.5