General - Schedule of Net Income Available to Shareholders (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders	$ 455	$ 506	$ (488)	$ 1,580
Less: Net Income allocated to restricted stock awards(a)	$ (3)	$ (3)	$ (9)	$ (9)
Basic Weighted Average Common Shares Outstanding	2,263	2,264	2,263	2,263
Basic Earnings (Loss) Per Common Share	$ 0.20	$ 0.22	$ (0.22)	$ 0.69
Class P Common Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders	$ 452	$ 503	$ (497)	$ 1,571
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	13		13