ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Apr. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017	Jan. 01, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (9,387)		$ (9,387)		$ (8,571)	$ (8,591)
Total Equity, Beginning		28,017	$ 29,589	28,017	$ 29,589	26,961	27,009		$ 27,229
Other comprehensive income (loss) before reclassifications				(58)	597
Amounts reclassified from accumulated other comprehensive income		150	65	299	151
Total other comprehensive income		(242)	440	241	748
Reclassification of stranded tax effects 3	$ 1,057
Other Comprehensive Income (Loss), Tax		68	45	82	104
Unrealized gains (losses) on investments
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		1	(35)	3	(47)
Total Equity, Beginning		(23)	51	(23)	51	17		$ 43
Other comprehensive income (loss) before reclassifications				(41)	38
Amounts reclassified from accumulated other comprehensive income		1	(22)	2	(30)
Total other comprehensive income				(39)	8
Other Comprehensive Income (Loss), Tax		(3)	(4)	(9)	4
Reclassification from AOCI, Current Period, Tax		0	13	(1)	17
Cumulative Translation Adjustments
Total Equity, Beginning		(1,682)	(1,755)	(1,682)	(1,755)	(1,481)		(2,381)
Other comprehensive income (loss) before reclassifications				(92)	632
Amounts reclassified from accumulated other comprehensive income				(2)	(6)
Total other comprehensive income				(94)	626
Other Comprehensive Income (Loss), Tax		25	8	20	26
Pension and other postretirement benefit plans
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		158	149	312	298
Total Equity, Beginning		(7,675)	(7,186)	(7,675)	(7,186)	(6,998)		(7,389)
Other comprehensive income (loss) before reclassifications				0	0
Amounts reclassified from accumulated other comprehensive income		124	101	250	203
Total other comprehensive income				250	203
Other Comprehensive Income (Loss), Tax		34	48	62	95
Reclassification from AOCI, Current Period, Tax		(34)	(48)	(62)	(95)
Derivative instruments
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax		32	(8)	59	(15)
Total Equity, Beginning		(7)	(184)	(7)	(184)	(109)		(95)
Other comprehensive income (loss) before reclassifications				75	(73)
Amounts reclassified from accumulated other comprehensive income		27	(8)	49	(16)
Total other comprehensive income				124	(89)
Other Comprehensive Income (Loss), Tax		12	(7)	9	(21)
Reclassification from AOCI, Current Period, Tax		(5)	0	(10)	(1)
Accumulated Other Comprehensive Loss
Total Equity, Beginning		$ (9,387)	$ (9,074)	(9,387)	(9,074)	(8,571)	$ (8,591)	$ (9,822)	$ (9,822)
Total other comprehensive income				241	$ 748
Accounting Standards Update 2018-02 [Domain]
Reclassification of stranded tax effects 3				(1,057)
Accounting Standards Update 2018-02 [Domain] | Unrealized gains (losses) on investments
Reclassification of stranded tax effects 3				(1)
Accounting Standards Update 2018-02 [Domain] | Cumulative Translation Adjustments
Reclassification of stranded tax effects 3				(107)
Accounting Standards Update 2018-02 [Domain] | Pension and other postretirement benefit plans
Reclassification of stranded tax effects 3				(927)
Accounting Standards Update 2018-02 [Domain] | Derivative instruments
Reclassification of stranded tax effects 3				$ (22)
Accounting Standards Update 2016-01 [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax						20
Total Equity, Beginning						$ 0