SUPPLEMENTAL FINANCIAL STATEMENT INFORMATION Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Disclosure Text Block Supplement [Abstract]
Temporary investments	$ 484		$ 484		$ 402
Allowance for doubtful accounts	77		77		81
Accumulated depreciation	20,400		20,400		20,500
Depreciation expense	305	$ 315	902	$ 930
Capital expenditures incurred but not yet paid			104		135
Interest payments			591	$ 606
Asset retirement obligation	$ 95		$ 95		$ 86