Debt (Details) (Credit Agreement dated March 28, 2013, USD $)	Sep. 30, 2014	Mar. 28, 2013
Credit Agreement dated March 28, 2013
Debt
Borrowing capacity, maximum		$ 1,250,000,000
Additional borrowing capacity	1,200,000,000
Absorption of reduction to shareholders' equity to remain in compliance with covenant	859,000,000
Amount borrowed	$ 0

Under the line of credit covenant's limit on debt to total capitalization ratio, permitted additional borrowing capacity beyond amounts already drawn as of the balance sheet date.

No definition available.

+ Details

Name:	mas_LineOfCreditCovenantAdditionalBorrowingCapacity
Namespace Prefix:	mas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Under the line of credit covenant's limit on debt to total capitalization ratio, amount of reduction in shareholders equity that the entity could absorb and still be in compliance as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	mas_LineOfCreditCovenantPotentialReductionInEquityThatWouldMaintainCompliance
Namespace Prefix:	mas_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant