STOCKHOLDERS' EQUITY STOCKHOLDERS' EQUITY - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ (9,219)	$ (9,146)	$ (9,219)	$ (9,146)		$ (9,885)
Other Comprehensive Income (Loss), Net of Tax	(231)	241	(127)	482
Transfer of Business Under Common Control			1,935	(276)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	(4)	(1)	(33)	9
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	60	(15)	60	(15)	$ 49	(51)	$ (23)	$ 17
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	16	5	125	(36)
Other Comprehensive Income (Loss), Net of Tax	11	8	111	(31)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	20	6	158	(45)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	(26)	(4)	(12)	(24)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(1,283)	(1,780)	(1,283)	(1,780)	(1,067)	(1,813)	(1,682)	(1,481)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(190)	(98)	(112)	(190)
Other Comprehensive Income (Loss), Net of Tax	(216)	(98)	(180)	(192)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(164)	(94)	(100)	(166)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	0	0	(10)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(7,527)	(7,552)	(7,527)	(7,552)	(7,635)	(7,965)	(7,675)	(6,998)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	24	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	108	123	331	373
Other Comprehensive Income (Loss), Net of Tax	108	123	355	373
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0	34	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	139	156	413	468
Reclassification from AOCI, Current Period, Tax	(31)	(33)	(82)	(95)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Tax	37	(45)	110	(44)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(469)	201	(469)	201	$ (335)	$ (56)	$ (7)	$ (109)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(150)	196	(435)	271
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	16	12	22	61
Other Comprehensive Income (Loss), Net of Tax	(134)	208	(413)	332
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(187)	241	(545)	315
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	20	16	30	75
Reclassification from AOCI, Current Period, Tax	(4)	(4)	(8)	(14)
Investment in nonconsolidated affiliates [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			45
Retained Earnings [Member] | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0	0	0	(1)
Retained Earnings [Member] | Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0	0	0	(107)
Transfer of Business Under Common Control	0	0	710	0
Retained Earnings [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0	0	0	(927)
Transfer of Business Under Common Control	0	0	83	0
Retained Earnings [Member] | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	0	0	0	(22)
Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(5)	3	(14)	5
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	(6)	4	(18)	7
Reclassification from AOCI, Current Period, Tax	1	(1)	4	(2)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (26)	$ 0	$ (68)	$ (2)