Debt Obligations Level 4 (Details) Debt Outstanding - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Synthetic Letter of Credit Facility	$ 47
ABL Facility [Domain]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	299
Non-Affiliated Debt [Abstract]
Long-Term	0	$ 0
Due Within One Year	0	0
6.625% First Priority Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Premium	3	4
Non-Affiliated Debt [Abstract]
Long-Term	1,553	1,554
Due Within One Year	0	0
10.00% First Priority Senior Notes Due 2020 [Member]
Non-Affiliated Debt [Abstract]
Long-Term	315	315
Due Within One Year	0	0
8.875% Senior Secured Notes Due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount	1	2
Non-Affiliated Debt [Abstract]
Long-Term	706	995
Due Within One Year	0	0
9.00% Second-Priority Senior Secured Notes Due 2020 [Member]
Non-Affiliated Debt [Abstract]
Long-Term	574	574
Due Within One Year	0	0
9.2% Debentures Due 2021 [Member]
Non-Affiliated Debt [Abstract]
Long-Term	74	74
Due Within One Year	0	0
7.875% Debentures Due 2023 [Member]
Non-Affiliated Debt [Abstract]
Long-Term	189	189
Due Within One Year	0	0
Australia Facility Due 2014 [Member]
Non-Affiliated Debt [Abstract]
Long-Term	0	29
Due Within One Year	51	3
Affiliated Debt [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity	7
Brazilian Bank Loans [Member]
Non-Affiliated Debt [Abstract]
Long-Term	14	5
Due Within One Year	26	42
Capital Leases [Member]
Non-Affiliated Debt [Abstract]
Long-Term	7	9
Due Within One Year	2	1
Other [Member]
Non-Affiliated Debt [Abstract]
Long-Term	3	5
Due Within One Year	28	34
Unamortized debt issuance costs
Non-Affiliated Debt [Abstract]
Long-Term	(38)	(51)
Due Within One Year	0	0
Total non-affiliated debt [Member]
Non-Affiliated Debt [Abstract]
Long-Term	3,397	3,698
Due Within One Year	$ 107	$ 80

Affiliated Debt [Abstract]

No definition available.

Name:	msc_AffiliatedDebtAbstract
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Balance Type:	na
Period Type:	duration

- Definition

Non-Affiliated Debt [Abstract]

+ References

No definition available.

+ Details

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Namespace Prefix:	msc_
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Balance Type:	na
Period Type:	duration

- Definition

synthetic letter of credit facility

+ References

No definition available.

+ Details

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Namespace Prefix:	msc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

+ Details

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

- Definition

Amount, after accumulated amortization, of debt premium.

+ References

+ Details

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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

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ 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. 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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: 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

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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 current. 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 210.5-02.19,20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=msc_A8875SeniorSecuredNotesDue2018Member
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Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=msc_A900SecondPrioritySeniorSecuredNotesDue2020Member
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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=msc_AustraliaFacilityDue2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_DebtInstrumentAxis=msc_BrazilianBankLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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- Details

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- Details

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