Earnings Per Share Net Income for Earnings Per Share Calculations - Basic and Diluted (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018		Sep. 30, 2019		Sep. 30, 2018
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (527)	$ (184)	$ (5,642)	[1]	$ (228)	[1]	$ (5,705)	[1]
Net (loss) income Attributable to Noncontrolling Interest, Continuing Operations	(11)		5		10		23
Net loss from Continuing Operations Available to Common Shareholders	(516)		(5,647)		(238)		(5,728)
Income (loss) from discontinued operations after income taxes	22		526		(695)		1,200
Income from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest	0		0		5		6
Net Income (loss) from Discontinued Operations Available to Common Shareholders	22		526		(700)		1,194
Net loss Available to Common Stockholders	$ (494)		$ (5,121)		$ (938)		$ (4,534)

[1] Periods prior to March 31, 2019 are on a pro forma basis, prepared in accordance with Article 11 of Regulation S-X.