PRO FORMA EARNINGS PER SHARE - Basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income	$ 92	$ 51	$ 269	$ 105
Weighted-average common shares outstanding - basic (in shares)	44.1	44.1	44.1	44.1
Weighted-average common shares outstanding - diluted (in shares)	44.1	44.1	44.1	44.1
Pro forma earnings per share - basic (in dollars per share)	$ 2.09	$ 1.16	$ 6.10	$ 2.38
Pro forma earnings per share - diluted (in dollars per share)	$ 2.09	$ 1.16	$ 6.10	$ 2.38