CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019
Income tax expense	$ 168	$ 136	$ 325	$ 255
ACCUMULATED DEFICIT | Cumulative Effect, Period of Adoption, Adjustment
Income tax expense					$ 2