INCOME TAXES - Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Total interest and penalties in the Consolidated Balance Sheet at January 1, Pretax	$ 121	$ 260	$ 233
Total interest and penalties in the Consolidated Statement of Income, Pretax	6	5	105
Total interest and penalties in the Consolidated Balance Sheet at December 31, Pretax	103	121	260
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	101	164	146
Total interest and penalties in the Consolidated Statement of Income, Net of tax	6	21	68
Total interest and penalties in the Consolidated Balance Sheet at December 31, Net of tax	85	101	164
Foreign penalties included in total interest and penalties in the balance sheet	2	3	3
State penalties included in total interest and penalties	$ 1	$ 3	$ 3