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Asset Impairment Charge - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended | 3 Months Ended
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Dec. 31, 2014 | Sep. 30, 2014
Finite-Lived Intangible Assets [Line Items] |  |
Non-cash asset impairment charge | $ 3,262 us-gaap_AssetImpairmentCharges |
Dresden Papier GmbH [Member] | Trade Name [Member] |  |
Finite-Lived Intangible Assets [Line Items] |  |
Non-cash asset impairment charge |  | $ 3,300 us-gaap_AssetImpairmentCharges / us-gaap_BusinessAcquisitionAxis = glt_DresdenPapierGmbhMember / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TradeNamesMember

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2420-110228 + Details
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- Details
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |