Represents period considered in determining the annual rate of return on the pension plan assets.

No definition available.

Name:	mas_DefinedBenefitPlanActualReturnOnPlanAssetsPeriod
Namespace Prefix:	mas_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Actual rate of return on plan assets reflecting the average rate of earnings on the funds invested for the benefits included in the benefit obligation.

+ References

No definition available.

+ Details

Name:	mas_DefinedBenefitPlanActualReturnOnPlanAssetsRate
Namespace Prefix:	mas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate used to adjust for the time value of money for the plan applied to the most significant portion of the liabilities.

+ References

No definition available.

+ Details

Name:	mas_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRateSignificantPortion
Namespace Prefix:	mas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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=28361610&loc=d3e1928-114920

+ Details

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

- Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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=28361610&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=28361610&loc=d3e2446-114920

+ Details

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

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=mas_AlternativeInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

EMPLOYEE RETIREMENT PLANS (Details 6)	12 Months Ended		120 Months Ended	132 Months Ended	12 Months Ended
EMPLOYEE RETIREMENT PLANS (Details 6)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2012
Employee Retirement Plans
Expected return on plan assets (as a percent)	7.25%	7.25%
Actual annual rate of return on pension plan assets (as a percent)	3.60%	13.60%	5.90%	5.00%
Period for actual annual rate of return on the Company's pension plan	10 years
Equity securities
Employee Retirement Plans
Asset allocation (as a percent)	46.00%
Debt securities
Employee Retirement Plans
Asset allocation (as a percent)	34.00%
Alternative investments
Employee Retirement Plans
Asset allocation (as a percent)	20.00%
Minimum
Employee Retirement Plans
Liabilities having a discount rate for obligations (as a percent)		4.20%	4.20%
Defined-benefit pension plans
Employee Retirement Plans
Discount rate for obligations (as a percent)	3.80%	4.40%	4.40%	3.80%	3.80%
Expected return on plan assets (as a percent)	7.25%	7.25%			7.25%
Discount rate for net periodic pension cost (as a percent)	4.40%	3.80%			4.40%
Defined-benefit pension plans \| Minimum
Employee Retirement Plans
Discount rate for obligations (as a percent)	2.00%	1.75%	1.75%	2.00%
Discount rate for net periodic pension cost (as a percent)	3.70%
Defined-benefit pension plans \| Maximum
Employee Retirement Plans
Discount rate for obligations (as a percent)	4.00%	4.80%	4.80%	4.00%