XML 16 R48.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Income Taxes - Summary of Tax Years that Remain Subject to Examination by Major Jurisdiction (Detail) | 9 Months Ended
--- | ---
Sep. 30, 2015
United States - Federal [Member] | United States [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2013 - 2014
Examination in progress | N/A
United States - State [Member] | United States [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010 - 2014
Examination in progress | N/A
Foreign Tax Authority [Member] | Canada [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010 - 2014
Examination in progress | N/A
Foreign Tax Authority [Member] | Germany [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2012 - 2014
Examination in progress | 2007 - 2011
Foreign Tax Authority [Member] | France [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2013 - 2014
Examination in progress | 2011 - 2012
Foreign Tax Authority [Member] | United Kingdom [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2013 - 2014
Examination in progress | N/A
Foreign Tax Authority [Member] | Philippines [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2012, 2014
Examination in progress | 2013

X
- Definition Income tax examination in progress. + References No definition available. + Details
Name: | glt_IncomeTaxExaminationInProgress
Namespace Prefix: | glt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Income tax examination not yet initiated. + References No definition available. + Details
Name: | glt_IncomeTaxExaminationNotYetInitiated
Namespace Prefix: | glt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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_IncomeTaxExaminationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_DomesticCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_DE
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_FR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_PH
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |