RETIREMENT BENEFITS - Net (Benefit) Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
U.S. | Pension Plans
Amortization of unrecognized
Total net (benefit) expense	$ (37)	$ (38)	$ (69)	$ (68)
U.S. | Postretirement Benefit Plans
Amortization of unrecognized
Total net (benefit) expense	7	1	11	7
U.S. | Qualified plans | Pension Plans
Service-related expense
Benefits earned during the period	0	0	1	1
Interest cost on benefit obligation	128	132	260	273
Expected return on plan assets	(217)	(218)	(433)	(436)
Amortization of unrecognized
Prior service benefit	0	0	0	0
Net actuarial loss (gain)	38	39	79	75
Curtailment loss (gain)	3	0	3	0
Settlement loss	0	0	0	0
Total net (benefit) expense	(48)	(47)	(90)	(87)
U.S. | Qualified plans | Postretirement Benefit Plans
Service-related expense
Benefits earned during the period	0	0	0	0
Interest cost on benefit obligation	8	5	14	13
Expected return on plan assets	(2)	(3)	(3)	(5)
Amortization of unrecognized
Prior service benefit	0	0	0	0
Net actuarial loss (gain)	1	(1)	0	(1)
Curtailment loss (gain)	0	0	0	0
Settlement loss	0	0	0	0
Total net (benefit) expense	7	1	11	7
U.S. | Nonqualified plans | Pension Plans
Amortization of unrecognized
Total net (benefit) expense	11	9	21	19
U.S. | Nonqualified plans | Postretirement Benefit Plans
Amortization of unrecognized
Total net (benefit) expense	0	0	0	0
Non-U.S. plans | Pension Plans
Amortization of unrecognized
Total net (benefit) expense	54	60	106	116
Non-U.S. plans | Postretirement Benefit Plans
Amortization of unrecognized
Total net (benefit) expense	11	10	22	21
Non-U.S. plans | Qualified plans | Pension Plans
Service-related expense
Benefits earned during the period	38	39	74	77
Interest cost on benefit obligation	74	73	145	146
Expected return on plan assets	(76)	(74)	(146)	(146)
Amortization of unrecognized
Prior service benefit	(1)	(1)	(2)	(1)
Net actuarial loss (gain)	15	20	31	39
Curtailment loss (gain)	0	0	0	(3)
Settlement loss	4	3	4	4
Total net (benefit) expense	54	60	106	116
Non-U.S. plans | Qualified plans | Postretirement Benefit Plans
Service-related expense
Benefits earned during the period	2	3	4	6
Interest cost on benefit obligation	25	24	49	48
Expected return on plan assets	(22)	(22)	(43)	(43)
Amortization of unrecognized
Prior service benefit	(3)	(3)	(5)	(6)
Net actuarial loss (gain)	9	8	17	16
Curtailment loss (gain)	0	0	0	0
Settlement loss	0	0	0	0
Total net (benefit) expense	11	10	22	21
Non-U.S. plans | Nonqualified plans | Pension Plans
Amortization of unrecognized
Total net (benefit) expense	0	0	0	0
Non-U.S. plans | Nonqualified plans | Postretirement Benefit Plans
Amortization of unrecognized
Total net (benefit) expense	$ 0	$ 0	$ 0	$ 0