Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Allowance for doubtful accounts receivable	$ 17	$ 20
Assets, variable interest entity	3,114	3,134
Liabilities, variable interest entity	$ 2,745	$ 2,760
Preferred Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, shares authorized	300,000,000	300,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)	3,000,000,000	3,000,000,000
Common Stock, shares issued (in shares)	85,537,477	85,205,012
Common Stock, shares outstanding (in shares)	85,537,477	85,205,012
Variable Interest Entities
Assets, variable interest entity	$ 733	$ 800
Liabilities, variable interest entity	$ 703	$ 771