XML 67 R8.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Consolidated Statements Of Shareholders' Equity (Parenthetical) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Consolidated Statements Of Shareholders' Equity [Abstract] |  |  |
Adjustment to retirement benefit liability, taxes | $ 30 | $ 40 | $ 108
Adjustment to post-retirement healthcare benefit liability, taxes | $ 27 | $ 290 | $ 74

X
- Definition Other Comprehensive Income Minimum Pension Liability Net Adjustment Tax 1 + References No definition available. + Details
Name: | rock_OtherComprehensiveIncomeMinimumPensionLiabilityNetAdjustmentTax1
Namespace Prefix: | rock_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Tax effect, net of reclassification adjustments, of pension and other postretirement benefit plans (gain) loss included in accumulated other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e640-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i-k) -URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementOfStockholdersEquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration