XML 30 R50.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Income Taxes - Summary of Tax Years that Remain Subject to Examination by Major Jurisdiction (Detail) | 6 Months Ended
--- | ---
Jun. 30, 2014
United States - Federal [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010, 2013
Examination in progress | 2011 - 2012
United States - State [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2009 - 2013
Canada [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010 - 2013
Examination in progress | 2009
Germany [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2012 - 2013
Examination in progress | 2007 - 2011
France [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010, 2013
Examination in progress | 2011 - 2012
United Kingdom [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2010 - 2013
Philippines [Member] |
Income Tax Examination [Line Items] |
Examinations not yet initiated | 2012 - 2013
Examination in progress | 2011

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
- Details
Name: | us-gaap_IncomeTaxExaminationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration