FAIR VALUE - Narrative (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Upper limit percentage of Level 3 assets to total invested assets	0.10%
Long-term debt, carrying value	$ 4,770	$ 3,792
Long-term debt, fair value	5,191	4,004
Short-term borrowings	150	300
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term borrowings	$ 150	$ 300