FAIR VALUE MEASUREMENTS (Other Fair Value Narrative) (Details) $ in Millions	Jun. 30, 2018 USD ($) hedge_fund	Dec. 31, 2017 USD ($)
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Number of hedge funds with reporting lag | hedge_fund	2
Entities that calculate net asset value per share, reporting lag, percent other investments	49.00%	44.00%
Senior notes	$ 1,377	$ 1,341
Notes payable	36
Estimate of fair value measurement
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Senior notes	1,352	$ 1,412
Notes payable	$ 36