DERIVATIVES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Net gain (pre-tax) on derivatives expected to be reclassified in next 12 months	$ 1
Derivative Financial Instruments, Liabilities
Derivative [Line Items]
Change in derivative liability balance	(349)
Derivative Financial Instruments, Assets
Derivative [Line Items]
Change in derivative asset value	$ (10)