Income Per Common Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator (basic and diluted):
Income from continuing operations	$ 94	$ 133
Less: Allocation to redeemable noncontrolling interest	6	0
Less: Allocation to unvested restricted stock awards	0	1
Income from continuing operations attributable to common shareholders	88	132
Income from discontinued operations, net	0	397
Less: Allocation to unvested restricted stock awards	0	3
Income from discontinued operations, net attributable to common shareholders	0	394
Net income attributable to common shareholders	$ 88	$ 526
Denominator:
Basic common shares (based upon weighted average) (in shares)	256	273
Add: Stock option dilution (in shares)	1	1
Diluted common shares (in shares)	257	274