Earnings per Share (Unaudited) Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (loss) income from continuing operations	$ (549)	$ 75
Net loss (income) from continuing operations attributable to noncontrolling interests	58	(45)
Undistributed earnings allocated to participating securities	(3)	(3)
Net (loss) income from continuing operations attributable to common stockholders	(494)	27
Net income from discontinued operations attributable to common stockholders	0	1
Net (loss) income attributable to common stockholders	$ (494)	$ 28
Basic weighted-average shares of common stock outstanding	1,452	1,451
Add shares issuable upon exercise or vesting of dilutive stock options and restricted stock units (RSUs)a	0	6
Diluted weighted-average shares of common stock outstanding	1,452	1,457
Basic and diluted net (loss) income per share attributable to common stockholders:
Continuing operations (in dollars per share)	$ (0.34)	$ 0.02
Discontinued operations (in dollars per share)	0	0
Earnings per share, basic (in dollars per share)	$ (0.34)	$ 0.02
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	10	3
Dilutive Securities Excluded from Computation of EPS Amount	40	39