General - Schedule of Net Income Available to Shareholders (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net (Loss) Income Available to Common Stockholders	$ (637)	$ 518	$ (943)	$ 1,074
Less: Net Income allocated to restricted stock awards(a)	$ (3)	$ (3)	$ (6)	$ (6)
Basic Weighted Average Common Shares Outstanding	2,261	2,262	2,263	2,262
Basic (Loss) Earnings Per Common Share	$ (0.28)	$ 0.23	$ (0.42)	$ 0.47
Class P Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net (Loss) Income Available to Common Stockholders	$ (640)	$ 515	$ (949)	$ 1,068
Unvested restricted stock awards | Class P Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Restricted stock awards outstanding	12		12