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	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator (basic and diluted):
Income from continuing operations	$ 734	$ 533	$ 493
Less: Allocation to unvested restricted stock awards	7	5	6
Net income available to common shareholders	$ 727	$ 528	$ 487
Denominator:
Basic common shares (based upon weighted average) (in shares)	305	314	326
Add: Stock option dilution (in shares)	2	4	4
Diluted common shares (in shares)	307	318	330