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, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator (basic and diluted):
Income from continuing operations	$ 76	$ 111	$ 109	$ 61	$ 86	$ 533	$ 124	$ 78	$ 357	$ 821	$ 259
Less: Allocation to unvested restricted stock awards									5	16	6
Income from continuing operations attributable to common shareholders									352	805	253
(Loss) income from discontinued operations, net									(2)	35	29
Less: Allocation to unvested restricted stock awards										(1)
(Loss) income from discontinued operations attributable to common shareholders									(2)	34	29
Net income available to common shareholders									$ 350	$ 839	$ 282
Denominator:
Basic common shares (based upon weighted average) (in shares)									338	349	350
Add: Stock option dilution (in shares)									3	3	2
Diluted common shares (in shares)									341	352	352