FAIR VALUE MEASUREMENTS (Schedule of Unrealized Gains (Losses) Related to Available-for-Sale Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 1,943	$ 1,885
Total Unrealized Gains	1,570	1,276
Total Unrealized Losses	(6)	(23)
Total Fair Value	3,507	3,138
Amount primarily related to deferred taxes on appreciation of investment value	491	408
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16	29
Total Unrealized Gains	0	0
Total Unrealized Losses	0	0
Total Fair Value	16	29
Global equity securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	496	568
Total Unrealized Gains	1,486	1,246
Total Unrealized Losses	(4)	(5)
Total Fair Value	1,978	1,809
Fixed-income securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,431	1,288
Total Unrealized Gains	84	30
Total Unrealized Losses	(2)	(18)
Total Fair Value	$ 1,513	$ 1,300