Debt Instrument, Covenant, EBITDA Ratio

No definition available.

Name:	swm_DebtInstrumentCovenantEBITDARatio
Namespace Prefix:	swm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of amortization expense attributable to 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(8))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(8))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

Name:	us-gaap_AmortizationOfFinancingCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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

- Definition

The amount of debt issuance costs that were incurred during a noncash or partial noncash transaction.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586

+ Details

Name:	us-gaap_DebtIssuanceCostsIncurredDuringNoncashOrPartialNoncashTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

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

- Definition

The effective interest rate at the end of the reporting period.

+ 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

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_InterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=swm_TermLoanA1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=swm_TermLoanA2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
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:

- Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	swm_InterestRatePeriodAxis=swm_InterestRatePeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	swm_InterestRatePeriodAxis=swm_InterestRatePeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Additional Information (Details)		1 Months Ended	3 Months Ended	6 Months Ended
Debt - Additional Information (Details)	Jan. 20, 2017 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jan. 01, 2019	Jul. 01, 2018	Apr. 01, 2018	Jan. 01, 2018	Dec. 31, 2016 USD ($)	Oct. 28, 2015 USD ($)
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time			2.31%	3.05%
Deferred debt issuance costs				$ 6,700,000					$ 7,000,000
Interest Expense [Member]
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 900,000	$ 900,000
Second Amended and Restated Credit Agreement [Member]
Debt Instrument [Line Items]
EBITDA ratio	4.25
Maximum borrowings under credit facility										$ 1,000,000,000
Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction	$ 600,000
Term Loan A-1 [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										100,000,000
Prepayment of amortization for term loan		$ 40,000,000
Average interest rate on outstanding borrowings				3.25%
Term Loan A-2 [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, face amount										$ 250,000,000
Interest rate										1.00%
Average interest rate on outstanding borrowings				3.50%
Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member]
Debt Instrument [Line Items]
Maximum borrowings under credit facility										$ 650,000,000
Revolving Credit Facility [Member] \| Revolving Credit Agreement - U.S. dollar borrowings [Member]
Debt Instrument [Line Items]
Average interest rate on outstanding borrowings				3.25%
Base Rate [Member] \| Term Loan A-1 [Member] \| Term Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				0.25%
Base Rate [Member] \| Term Loan A-1 [Member] \| Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.50%
Base Rate [Member] \| Term Loan A-2 [Member] \| Term Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				0.50%
Base Rate [Member] \| Term Loan A-2 [Member] \| Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.75%
Base Rate [Member] \| Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				0.25%
Base Rate [Member] \| Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.50%
London Interbank Offered Rate (LIBOR) [Member] \| Term Loan A-1 [Member] \| Term Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.25%
London Interbank Offered Rate (LIBOR) [Member] \| Term Loan A-1 [Member] \| Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				2.50%
London Interbank Offered Rate (LIBOR) [Member] \| Term Loan A-2 [Member] \| Term Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.50%
London Interbank Offered Rate (LIBOR) [Member] \| Term Loan A-2 [Member] \| Term Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				2.75%
London Interbank Offered Rate (LIBOR) [Member] \| Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				1.25%
London Interbank Offered Rate (LIBOR) [Member] \| Revolving Credit Facility [Member] \| Second Amended and Restated Credit Agreement [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable interest rate				2.50%
Forecast [Member] \| Second Amended and Restated Credit Agreement [Member]
Debt Instrument [Line Items]
EBITDA ratio					3.00	3.50	3.75	4.00
Interest rate, first two years [Member] \| Term Loan A-1 [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Interest rate										5.00%
Interest rate, final three years [Member] \| Term Loan A-1 [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Interest rate										10.00%