Percentage, expected long-term rate of return on securities.

No definition available.

Name:	mmm_DefinedBenefitExpectedReturnOnAssetsPercentage
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the actual return on the plan assets.

+ References

No definition available.

+ Details

Name:	mmm_DefinedBenefitPlanActualAverageAnnualReturn
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	mmm_DefinedBenefitPlanAssetsExpectedLongTermRateOfReturnAbstract
Namespace Prefix:	mmm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The average annual actual return on plan assets over the past ten years, percentage.

+ References

No definition available.

+ Details

Name:	mmm_DefinedBenefitPlanAverageAnnualActualReturnOnPlanAssetsOverTenYearsPercentage
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The average annual actual return on plan assets over the past twenty-five years, percentage.

+ References

No definition available.

+ Details

Name:	mmm_DefinedBenefitPlanAverageAnnualActualReturnOnPlanAssetsOverTwentyFiveYearsPercentage
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the percentage change in assumed discount rate from the prior year used in calculating the benefit obligation.

+ References

No definition available.

+ Details

Name:	mmm_DefinedBenefitPlanPercentageChangeInDiscountRateUsedCalculatingBenefitObligationFromPreviousFiscalYear
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum percentage of medical inflation absorbed by the company in a year.

+ References

No definition available.

+ Details

Name:	mmm_MaximumPercentageMedicalInflationAbsorbedByCompanyInYear
Namespace Prefix:	mmm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The estimated amount of pension contributions for the next fiscal period.

+ References

No definition available.

+ Details

Name:	mmm_PensionContributionsForNextFiscalYear
Namespace Prefix:	mmm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount included in accumulated other comprehensive income (AOCI) related to transition obligation (asset) expected to be recognized as components of net periodic benefit cost (credit) for the fiscal year that follows the most recent annual statement of financial position.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAmortizationOfNetTransitionAssetObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The interest rate used to adjust for the time value of money.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Long-Term Rate of Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512013

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(3)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount included in accumulated other comprehensive income (AOCI) related to prior service cost (credit) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ 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 (d)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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Pension and Postretirement Benefit Plans (Components of net periodic benefit cost and other information) (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Company's assumption for the expected return on plan assets
Maximum percentage of medical inflation absorbed by the company in year	3.00%
Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 210	$ 476
Qualified and Non-qualified Pension Benefits \| Maximum
Company's assumption for the expected return on plan assets
Estimated pension contributions for next fiscal year	200
Qualified and Non-qualified Pension Benefits \| Minimum
Company's assumption for the expected return on plan assets
Estimated pension contributions for next fiscal year	100
United States Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	45	53
Amounts expected to be amortized from accumulated other comprehensive income into net periodic benefit costs over next fiscal year
Amortization of transition (asset) obligation	0
Amortization of prior service cost (benefit)	(24)
Amortization of net actuarial (gain) loss	408
Total amortization expected over the next fiscal year	384
Weighted-average assumptions used to determine benefit obligations
Discount rate	4.10%	4.98%	4.14%
Compensation rate increase	4.10%	4.00%	4.00%
Percentage increase (decrease) in discount rate obligation from the prior year	(0.88%)
Weighted-average assumptions used to determine net cost for years ended
Discount rate	4.98%	4.14%	4.15%
Expected return on assets	7.75%	8.00%	8.25%
Compensation rate increase	4.00%	4.00%	4.00%
United States Qualified Pension Benefits
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	7.75%
Rate of return on plan assets	13.00%	6.00%	13.60%
Average annual actual return on plan assets over the past 10 years	8.70%
Average annual actual return on plan assets over the past 25 years	10.00%
United States Qualified Pension Benefits \| Global equities
Asset Allocation assumption
Asset allocation assumption for next fiscal year	26.00%
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	7.00%
United States Qualified Pension Benefits \| Private equities
Asset Allocation assumption
Asset allocation assumption for next fiscal year	17.00%
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	12.00%
United States Qualified Pension Benefits \| Fixed income securities
Asset Allocation assumption
Asset allocation assumption for next fiscal year	44.00%
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	4.50%
United States Qualified Pension Benefits \| Absolute return investments
Asset Allocation assumption
Asset allocation assumption for next fiscal year	13.00%
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	6.75%
International Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	165	423
Amounts expected to be amortized from accumulated other comprehensive income into net periodic benefit costs over next fiscal year
Amortization of transition (asset) obligation	(1)
Amortization of prior service cost (benefit)	(15)
Amortization of net actuarial (gain) loss	154
Total amortization expected over the next fiscal year	138
Weighted-average assumptions used to determine benefit obligations
Discount rate	3.11%	4.02%	3.78%
Compensation rate increase	3.33%	3.35%	3.31%
Weighted-average assumptions used to determine net cost for years ended
Discount rate	4.02%	3.78%	4.58%
Expected return on assets	5.83%	5.87%	6.38%
Compensation rate increase	3.35%	3.31%	3.52%
Postretirement Benefits
Benefit Plan Information
Company contributions	5	6
Amounts expected to be amortized from accumulated other comprehensive income into net periodic benefit costs over next fiscal year
Amortization of transition (asset) obligation	0
Amortization of prior service cost (benefit)	(33)
Amortization of net actuarial (gain) loss	77
Total amortization expected over the next fiscal year	$ 44
Weighted-average assumptions used to determine benefit obligations
Discount rate	4.07%	4.83%	4.00%
Percentage increase (decrease) in discount rate obligation from the prior year	(0.76%)
Weighted-average assumptions used to determine net cost for years ended
Discount rate	4.83%	4.00%	4.04%
Expected return on assets	7.11%	7.19%	7.30%