STOCK-BASED COMPENSATION - Long-Term Stock Awards (Details) - Long-term stock awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unvested stock award shares
Balance at the beginning of the period (in shares)	4,000,000	5,000,000	6,000,000
Granted (in shares)	853,690	1,000,000	1,000,000
Vested (in shares)	2,000,000	2,000,000	2,000,000
Forfeited (in shares)		0	0
Forfeitures upon spin off (in shares)	0	0	1,000,000
Modification upon spin off (in shares)	0	0	1,000,000
Balance at the end of the period (in shares)	3,000,000	4,000,000	5,000,000
Weighted average grant date fair value
Balance at the beginning of the period (in dollars per share)	$ 20	$ 17	$ 18
Granted (in dollars per share)	34	26	26
Vested (in dollars per share)	18	16	17
Forfeited (in dollars per share)	24	20	18
Forfeitures upon spin off (in dollars per share)	0	0	20
Balance at the end of the period (in dollars per share)	$ 24	$ 20	$ 17
Additional disclosures
Total unrecognized compensation expense	$ 46	$ 43	$ 42
Remaining weighted average vesting period	3 years	3 years	3 years
Total market value (at the vesting date) of stock award shares	$ 45	$ 43	$ 54