INCOME TAXES - Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense	$ 489	$ 423	$ 403
Tax effect of changes in OCI	(168)	(12)	154
Total comprehensive income tax expense	$ 321	$ 411	$ 557