XML 48 R34.htm IDEA: XBRL DOCUMENT
v3.21.1

Stock-Based Compensation (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2021
Restricted Stock Units (RSU) and Performance Share Awards (PSAs) [Member] |
Summary of Share Based Compensation Activity | The following table summarizes RSU and PSA activity during periods indicated:
Units |  | 2021 |  |  |  | 2020 |
Balance at January 1, |  |  | 1,071,652 |  |  |  |  | 896,463 |
Granted |  |  | 287,805 |  |  |  |  | 294,315 |
Forfeited |  |  | (90,355 | ) |  |  |  | (17,455 | )
Shares delivered |  |  | (123,038 | ) |  |  |  | (78,509 | )
Balance at March 31, |  |  | 1,146,064 |  |  |  |  | 1,094,814 |
Compensation Expense for Stock Option Activity Included in Continuing Operations | The following table sets forth aggregate RSU and PSA compensation expense included in continuing operations for the periods indicated:
|  | March 31 |
In thousands |  | 2021 |  |  |  | 2020 |
Three months ended |  | $ | 1,208 |  |  |  | $ | 1,085 |
Stock Only Stock Appreciation Rights (SOSARs) [Member] |
Summary of Share Based Compensation Activity | The following table sets forth information related to outstanding SOSARS:
|  | 2021 |  |  | 2020 |
SOSARS |  | Shares |  |  |  | Wtd Avg Exercise Price |  |  | Shares |  |  | Wtd Avg Exercise Price |
Outstanding at January 1, |  |  | 1,082,413 |  |  |  | $ | 20.40 |  |  |  | 1,291,947 |  |  | $ | 20.05 |
Granted |  |  | — |  |  |  |  | — |  |  |  | — |  |  |  | — |
Exercised |  |  | — |  |  |  |  | — |  |  |  | (44,710 | ) |  |  | 12.94 |
Canceled / forfeited |  |  | — |  |  |  |  | — |  |  |  | (2,841 | ) |  |  | 17.27 |
Outstanding at March 31, |  |  | 1,082,413 |  |  |  | $ | 20.40 |  |  |  | 1,244,396 |  |  | $ | 20.31 |

X
- Definition Tabular disclosure of share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=glt_RestrictedStockUnitsAndPerformanceShareAwardsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_StockAppreciationRightsSARSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |