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Condensed Consolidating Financial Statements - Additional Information (Detail) | Sep. 30, 2018 | Oct. 03, 2012
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PHG Tea Leaves, Inc. [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percentage owned in domestic subsidiaries | 100.00% |
Mollanvick, Inc. [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percentage owned in domestic subsidiaries | 100.00% |
Glatfelter Holdings, LLC [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percentage owned in domestic subsidiaries | 100.00% |
Glatfelter Composite Fibers N. A., Inc. [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percentage owned in domestic subsidiaries | 100.00% |
Glatfelter Advanced Materials N.A., Inc. [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percentage owned in domestic subsidiaries | 100.00% |
5.375% Notes [Member] |  |
Schedule of Equity Method Investments [Line Items] |  |
Percent on aggregate principal amount of outstanding | 5.375% | 5.375%

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