STOCK-BASED COMPENSATION - Stock Option Shares Outstanding and Exercisable (Details) shares in Millions	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	$ 7
Exercise price range, high end of range (in dollars per share)	$ 29
Option Shares Outstanding, Number of Shares | shares	12
Option Shares Outstanding, Weighted Average Remaining Option Term	3 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 17
Option Shares Exercisable, Number of Shares | shares	10
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 18
Range One
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	7
Exercise price range, high end of range (in dollars per share)	$ 18
Option Shares Outstanding, Number of Shares | shares	7
Option Shares Outstanding, Weighted Average Remaining Option Term	4 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12
Option Shares Exercisable, Number of Shares | shares	6
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 12
Range Two
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	20
Exercise price range, high end of range (in dollars per share)	$ 23
Option Shares Outstanding, Number of Shares | shares	2
Option Shares Outstanding, Weighted Average Remaining Option Term	3 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 23
Option Shares Exercisable, Number of Shares | shares	1
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 23
Range Three
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	25
Exercise price range, high end of range (in dollars per share)	$ 27
Option Shares Outstanding, Number of Shares | shares	3
Option Shares Outstanding, Weighted Average Remaining Option Term	1 year
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 27
Option Shares Exercisable, Number of Shares | shares	3
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 27
Range Four
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	28
Exercise price range, high end of range (in dollars per share)	$ 29
Option Shares Outstanding, Weighted Average Remaining Option Term	0 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 29
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 29