XML 128 R108.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Other Long-Term Assets - Summary of Other Long-Term Assets (Detail) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Other Assets Noncurrent [Abstract] |  |
Pension | $ 43,341 | $ 66,382
Other | 24,006 | 14,745
Total | $ 67,347 | $ 81,127

X
- Definition Prepaid pension cost. + References No definition available. + Details
Name: | glt_PrepaidPensionCost
Namespace Prefix: | glt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of other miscellaneous assets expected to be realized or consumed after one year or normal operating cycle, if longer. + References No definition available. + Details
Name: | us-gaap_OtherAssetsMiscellaneousNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of noncurrent assets classified as other. + 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 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_OtherAssetsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_OtherAssetsNoncurrentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration