XML 84 R67.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Long-Term Debt - Summary of Long-Term Debt (Parenthetical) (Detail) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Dec. 31, 2017
5.375% Notes, Due Oct. 2020 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Oct. 31, 2020 |
Interest rate on debt | 5.375% | 5.375%
2.40% Term Loan, Due Jun. 2022 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Jun. 30, 2022 |
Interest rate on debt | 2.40% | 2.40%
2.05% Term Loan, Due Mar. 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Mar. 31, 2023 |
Interest rate on debt | 2.05% | 2.05%
1.30% Term Loan, Due Jun. 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Jun. 30, 2023 |
Interest rate on debt | 1.30% | 1.30%
1.55% Term Loan, Due Sep. 2025 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Sep. 30, 2025 |
Interest rate on debt | 1.55% | 1.55%
Revolving Credit Facility, Due Mar. 2020 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt, maturity date | Mar. 31, 2020 |

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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

X
- 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

X
- Definition Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_DebtInstrumentMaturityDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=glt_FivePointThreeSevenFivePercentNotesDueOctoberTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=glt_TwoPointFourZeroPercentTermLoanDueJuneTwoThousandTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=glt_TwoPointZeroFivePercentTermLoanDueMarchTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=glt_OnePointThreeZeroPercentageTermLoanDueJuneTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=glt_OnePointFiveFivePercentageTermLoanDueSeptemberTwoThousandTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=glt_RevolvingCreditFacilityDueMarchTwoThousandTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |