CONSOLIDATED STATEMENTS OF MEMBER'S EQUITY (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019
Income tax expense (benefit)	$ 37	$ 42	$ 150	$ 147
MEMBER'S EQUITY | Cumulative Effect, Period of Adoption, Adjustment
Income tax expense (benefit)					$ (2)