EARNINGS PER COMMON SHARE - Reconciliations of the Numerators and Denominators Used in the Computations of Basic and Diluted Earnings per Common Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator (basic and diluted):
Income from continuing operations	$ 158	$ 163	$ 211	$ 107	$ 172	$ 150	$ 178	$ 136	$ 639	$ 636	$ 426
Less: Allocation to unvested restricted stock awards									4	6	4
Net income available to common shareholders									$ 929	$ 727	$ 528
Denominator:
Basic common shares (based upon weighted average) (in shares)									287	305	314
Add: Stock option dilution (in shares)									1	2	4
Diluted common shares (in shares)									288	307	318
Loss (Income) from Continuing Operations Attributable To Common Shareholders									$ 635	$ 630	$ 422
Income from discontinued operations, net									296	98	107
Allocation To Unvested Restricted Stock Awards Discontinuing Operations									2	1	1
Income (Loss) from Discontinued Operations Attributable to Common Stockholders									$ 294	$ 97	$ 106