Goodwill and Intangibles Level 4 (Details) - Schedule of Intangible Assets (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	$ 14us-gaap_AmortizationOfIntangibleAssets	$ 13us-gaap_AmortizationOfIntangibleAssets	$ 13us-gaap_AmortizationOfIntangibleAssets
Finite-Lived Intangible Assets, Gross	246	230
Impairment of Intangible Assets, Finite-lived	(17)msc_AccumulatedImpairments	(17)msc_AccumulatedImpairments
Finite-Lived Intangible Assets, Accumulated Amortization	(148)	(131)
Intangible Assets, Net (Excluding Goodwill)	81	82
Patents and Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	112	112
Impairment of Intangible Assets, Finite-lived	0	0
Finite-Lived Intangible Assets, Accumulated Amortization	(78)	(70)
Intangible Assets, Net (Excluding Goodwill)	34	42
Customer Lists and Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	109	93
Impairment of Intangible Assets, Finite-lived	(17)	(17)
Finite-Lived Intangible Assets, Accumulated Amortization	(62)	(54)
Intangible Assets, Net (Excluding Goodwill)	30	22
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	25	25
Impairment of Intangible Assets, Finite-lived	0	0
Finite-Lived Intangible Assets, Accumulated Amortization	(8)	(7)
Intangible Assets, Net (Excluding Goodwill)	$ 17	$ 18

Accumulated Impairments

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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-Name Accounting Standards Codification

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

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