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Segment and Geographic Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013 Customer	Dec. 31, 2012 Customer	Dec. 31, 2011 Customer
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of customers accounting for percentage of net sales	0	0	0
Customers accounted for certain percentage in net sales	10.00%	10.00%	10.00%
Advanced Airlaid Materials [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of customers accounting for percentage of net sales	1	1	1

X

- Definition

Entity wide revenue major customer threshold percentage.

+ References

No definition available.

+ Details

Name:	glt_EntityWideRevenueMajorCustomerPercentageThreshold
Namespace Prefix:	glt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of customers accounting for percentage of net sales.

+ References

No definition available.

+ Details

Name:	glt_NumberOfCustomersAccountingForPercentageOfNetSales
Namespace Prefix:	glt_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_SegmentReportingRevenueReconcilingItemLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration