Condensed Consolidated Statements of Members' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Class A Units	Common Class A-1 Units	Common Class B Units	Accumulated Other Comprehensive (Loss) Income
Balance at Dec. 31, 2019	$ 805	$ 804	$ 15	$ 11	$ (25)
Balance, units at Dec. 31, 2019		123,700	1,683	1,107
Comprehensive (loss) income, net of tax	(72)	$ (21)			(51)
Restricted share units vested, net of units withheld in lieu of taxes, units			11	15
Share-based compensation expense	2			$ 2
Balance at Mar. 31, 2020	735	$ 783	$ 15	$ 13	(76)
Balance, units at Mar. 31, 2020		123,700	1,694	1,122
Balance at Dec. 31, 2019	805	$ 804	$ 15	$ 11	(25)
Balance, units at Dec. 31, 2019		123,700	1,683	1,107
Comprehensive (loss) income, net of tax	(124)
Balance at Sep. 30, 2020	679	$ 716	$ 13	$ 14	(64)
Balance, units at Sep. 30, 2020		123,700	1,798	1,719
Balance at Mar. 31, 2020	735	$ 783	$ 15	$ 13	(76)
Balance, units at Mar. 31, 2020		123,700	1,694	1,122
Comprehensive (loss) income, net of tax	(31)	$ (25)			(6)
Distribution of members' equity	(1)	(1)
Restricted share units vested, net of units withheld in lieu of taxes	(1)		$ (1)
Restricted share units vested, net of units withheld in lieu of taxes, units			157	209
Unit repurchases	(3)		$ (2)	$ (1)
Unit repurchases, units			(55)	(88)
Share-based compensation expense	2		$ 1	$ 1
Balance at Jun. 30, 2020	701	$ 757	$ 13	$ 13	(82)
Balance, units at Jun. 30, 2020		123,700	1,796	1,243
Comprehensive (loss) income, net of tax	(21)	$ (39)			18
Distribution of members' equity	(2)	(2)
Restricted share units vested, net of units withheld in lieu of taxes, units			2	476
Share-based compensation expense	1			$ 1
Balance at Sep. 30, 2020	679	$ 716	$ 13	$ 14	(64)
Balance, units at Sep. 30, 2020		123,700	1,798	1,719
Balance at Dec. 31, 2020	683	$ 699	$ 12	$ 14	(42)
Balance, units at Dec. 31, 2020		123,700	1,800	1,736
Comprehensive (loss) income, net of tax		$ (21)			21
Restricted share units vested, net of units withheld in lieu of taxes, units			1	50
Unit repurchases	(2)		$ (1)	$ (1)
Unit repurchases, units			(75)	(89)
Share-based compensation expense	2			$ 2
Balance at Mar. 31, 2021	683	$ 678	$ 11	$ 15	(21)
Balance, units at Mar. 31, 2021		123,700	1,726	1,697
Balance at Dec. 31, 2020	683	$ 699	$ 12	$ 14	(42)
Balance, units at Dec. 31, 2020		123,700	1,800	1,736
Comprehensive (loss) income, net of tax	6
Balance at Jun. 30, 2021	691	$ 674	$ 11	$ 17	(11)
Balance, units at Jun. 30, 2021		123,700	1,817	2,088
Balance at Mar. 31, 2021	683	$ 678	$ 11	$ 15	(21)
Balance, units at Mar. 31, 2021		123,700	1,726	1,697
Comprehensive (loss) income, net of tax	6	$ (4)			10
Restricted share units vested, net of units withheld in lieu of taxes	(1)		$ (1)
Restricted share units vested, net of units withheld in lieu of taxes, units			91	391
Share-based compensation expense	3		$ 1	$ 2
Balance at Jun. 30, 2021	691	$ 674	$ 11	$ 17	(11)
Balance, units at Jun. 30, 2021		123,700	1,817	2,088
Comprehensive (loss) income, net of tax	(110)
Share-based compensation expense	$ 15
Balance at Sep. 30, 2021					$ 3