Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Allowance for doubtful accounts receivable	$ 4	$ 2
Variable interest entities - assets	10,853	11,290
Variable interest entities - liabilities	$ 5,798	$ 4,839
Common stock, par value (per share)	$ 0.01	$ 0.01
Common stock, authorized shares	6,000,000,000	6,000,000,000
Common stock, issued shares	235,914,952	239,589,639
Common stock, outstanding shares	235,613,445	239,386,877
Consolidated VIEs [Member]
Variable interest entities - assets	$ 234	$ 242
Variable interest entities - liabilities	$ 217	$ 219