XML 34 R79.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Income Taxes - Schedule of Unrecognized Tax Benefit (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2013
--- | ---
Income Tax Disclosure [Abstract] |
Reserve for an uncertain tax position | $ 1.3

X
- Definition Reserve for uncertain tax position recorded in purchase accounting to acquisition. + References No definition available. + Details
Name: | glt_ReserveForUncertainTaxPositionRecordedInPurchaseAccountingToAcquisition
Namespace Prefix: | glt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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