INCOME TAXES - Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Total interest and penalties in the Consolidated Balance Sheet at January 1, Pretax	$ 260	$ 233	$ 269
Total interest and penalties in the Consolidated Statement of Income, Pretax	5	105	(29)
Total interest and penalties in the Consolidated Balance Sheet at December 31, Pretax	121	260	233
Reconciliation of Unrecognized Tax Benefits, Including Amounts Pertaining to Examined Tax Returns, Net of Tax [Roll Forward]
Total interest and penalties in the Consolidated Balance Sheet at January 1, Net of tax	164	146	169
Total interest and penalties in the Consolidated Statement of Income, Net of tax	21	68	(18)
Total interest and penalties in the Consolidated Balance Sheet at December 31, Net of tax	101	164	146
Foreign penalties included in total interest and penalties in the balance sheet	3	3	3
State penalties included in total interest and penalties	$ 3	$ 3	$ 3