STOCK-BASED COMPENSATION - Stock Option Shares Outstanding and Exercisable (Details) shares in Millions	12 Months Ended
	Dec. 31, 2017 $ / 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)	$ 34
Option Shares Outstanding, Number of shares (in shares) | shares	5
Option Shares Outstanding, Weighted Average Remaining Option Term	4 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 16
Option Shares Exercisable, Number of Shares (in shares) | shares	4
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 13
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 (in shares) | shares	3
Option Shares Outstanding, Weighted Average Remaining Option Term	3 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12
Option Shares Exercisable, Number of Shares (in shares) | shares	4
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 (in shares) | shares	1
Option Shares Outstanding, Weighted Average Remaining Option Term	7 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 22
Option Shares Exercisable, Number of Shares (in shares) | shares	0
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 22
Range Three
Stock-based compensation
Exercise price range, low end of range (in dollars per share)	26
Exercise price range, high end of range (in dollars per share)	$ 34
Option Shares Outstanding, Number of shares (in shares) | shares	1
Option Shares Outstanding, Weighted Average Remaining Option Term	9 years
Option Shares Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 29
Option Shares Exercisable, Number of Shares (in shares) | shares	0
Option Shares Exercisable, Weighted Average Exercise price (in dollars per share)	$ 26