Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

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

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ 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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=msc_A13.75SeniorSecuredNotesdue2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msc_A8875SeniorSecuredNotesDue2018Member
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- Details

Name:	us-gaap_DebtInstrumentAxis=msc_A10.375FirstPrioritySenionSecuredNotesdue2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=msc_ABLFacilityDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=msc_DebtRefinancingTransactionsMember
Namespace Prefix:
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Debt Obligations 2017 Refinancing Transactions (Details) - USD ($) $ in Millions	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt	$ 3,612		$ 3,397
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		$ 3
13.75% Senior Secured Notes due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	225		0
8.875% Senior Secured Notes Due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt	0		706
10.375% First-Priority Senion Secured Notes due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	560		0
ABL Facility [Domain]
Debt Instrument [Line Items]
Long-term debt	124		0
Line of Credit Facility, Maximum Borrowing Capacity	350		$ 400
Debt Refinancing Transactions [Member] \| 13.75% Senior Secured Notes due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt		225
Debt Refinancing Transactions [Member] \| 10.375% First-Priority Senion Secured Notes due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 75	$ 485