Shareholders' Equity - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Common stock dividends			$ 800,000,000
Dividends paid on preferred stock (Note 11)		$ 45,000,000
Preferred stock par value (in dollars per share)	$ 0.01		$ 0.01		$ 0.01
Proceeds from issuance of preferred stock			$ 492,000,000	$ 0
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Dividends paid on preferred stock (Note 11)			$ 58,000,000	58,000,000
Preferred stock shares issued	1,000,000		1,000,000		1,000,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Dividends paid on preferred stock (Note 11)			$ 32,000,000	$ 33,000,000
Preferred stock shares issued	500,000		500,000		500,000
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock shares issued	500,000		500,000		0
Preferred stock par value (in dollars per share)	$ 0.01		$ 0.01
Liquidation preference (in dollars per share)	$ 1,000		$ 1,000
Proceeds from issuance of preferred stock	$ 492,000,000
Preferred stock dividend rate	5.70%
Series C Preferred Stock [Member] | US Treasury Interest Rate [Member]
Class of Stock [Line Items]
Variable dividend payment rate	4.997