RETIREMENT-RELATED BENEFITS - Net Periodic Cost (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Pension Plans
Components of net periodic (income)/cost of the retirement-related benefit plans
Interest cost		$ 2,048	$ 2,028	$ 2,211
Expected return on plan assets		(3,689)	(3,953)	(4,096)
Amortization of prior service costs/(credits)		10	10	10
Recognized actuarial losses		1,314	1,654	1,056
Total net periodic (income)/cost of defined benefit plans		(317)	(261)	(818)
Non-US Pension Plans
Components of net periodic (income)/cost of the retirement-related benefit plans
Service cost		420	454	449
Interest cost		1,035	1,075	1,533
Expected return on plan assets		(1,867)	(1,919)	(2,247)
Amortization of transition assets		0	0	0
Amortization of prior service costs/(credits)		(106)	(98)	(111)
Recognized actuarial losses		1,408	1,581	1,400
Curtailments and settlements		22	35	26
Multi-employer plans/other costs		126	293	217
Total net periodic (income)/cost of defined benefit plans		1,039	1,421	1,267
Non-US Pension Plans \| Litigation in Spain regarding defined benefit and defined contribution plans \| SG&A expense
Components of net periodic (income)/cost of the retirement-related benefit plans
Multi-employer plans/other costs	$ 56	56	233	148
U.S. Nonpension Postretirement Benefit Plans
Components of net periodic (income)/cost of the retirement-related benefit plans
Service cost		17	24	26
Interest cost		165	163	187
Expected return on plan assets		0	0	0
Amortization of prior service costs/(credits)		(7)	(7)	(7)
Recognized actuarial losses		20	39	0
Total net periodic (income)/cost of defined benefit plans		195	218	206
Non-U.S. Nonpension Postretirement Benefit Plans
Components of net periodic (income)/cost of the retirement-related benefit plans
Service cost		5	7	7
Interest cost		51	50	63
Expected return on plan assets		(6)	(7)	(9)
Amortization of transition assets		0	0	0
Amortization of prior service costs/(credits)		(5)	(5)	(5)
Recognized actuarial losses		9	10	11
Curtailments and settlements		(38)	0	0
Total net periodic (income)/cost of defined benefit plans		$ 16	$ 55	$ 66

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Prior Service Cost
-URI http://asc.fasb.org/extlink&oid=49177896

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- Definition

The amount of the transition obligation or asset recognized in net periodic benefit cost.

+ References

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512171

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(2)
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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
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- Definition

Amount of other defined benefit plan costs.

+ References

No definition available.

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- Definition

Amount of net gain (loss) recognized in net periodic benefit cost due to settlements and curtailments. Curtailments result from an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services. Settlements result from an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Service Cost (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6525008

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-Name Accounting Standards Codification
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