XML 71 R83.htm IDEA: XBRL DOCUMENT v2.4.1.9
Other Postretirement Benefits (Changes in the Accumulated Postretirement Benefit Obligation) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Projected benefit obligation at $ 2,179us-gaap_DefinedBenefitPlanBenefitObligation $ 2,478us-gaap_DefinedBenefitPlanBenefitObligation $ 2,653us-gaap_DefinedBenefitPlanBenefitObligation
Service cost 0us-gaap_DefinedBenefitPlanServiceCost 0us-gaap_DefinedBenefitPlanServiceCost 0us-gaap_DefinedBenefitPlanServiceCost
Interest cost 88us-gaap_DefinedBenefitPlanInterestCost 80us-gaap_DefinedBenefitPlanInterestCost 110us-gaap_DefinedBenefitPlanInterestCost
Actuarial (gains) losses 9us-gaap_DefinedBenefitPlanActuarialGainLoss (58)us-gaap_DefinedBenefitPlanActuarialGainLoss 50us-gaap_DefinedBenefitPlanActuarialGainLoss
Benefits paid (315)us-gaap_DefinedBenefitPlanBenefitsPaid (321)us-gaap_DefinedBenefitPlanBenefitsPaid (335)us-gaap_DefinedBenefitPlanBenefitsPaid
Projected benefit obligation at 1,961us-gaap_DefinedBenefitPlanBenefitObligation 2,179us-gaap_DefinedBenefitPlanBenefitObligation 2,478us-gaap_DefinedBenefitPlanBenefitObligation
Fair value of plan assets 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Under funded status (1,961)us-gaap_DefinedBenefitPlanFundedStatusOfPlan (2,179)us-gaap_DefinedBenefitPlanFundedStatusOfPlan (2,478)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Unamortized prior service cost 24us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax 39us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax 53us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
Unrecognized actuarial gain (179)us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax (188)us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax (130)us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
Net amount recognized (2,116)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet (2,328)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet (2,555)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
Other Postretirement Benefits      
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]      
Projected benefit obligation at 5,900us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
5,954us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
5,120us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Service cost 16us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
16us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
15us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Interest cost 255us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
203us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
224us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Plan amendments 0rock_DefinedBenefitPlanPlanAmendmentsAndCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
603rock_DefinedBenefitPlanPlanAmendmentsAndCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
0rock_DefinedBenefitPlanPlanAmendmentsAndCurtailments
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Actuarial (gains) losses 2,387us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
(553)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
899us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Benefits paid (356)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
(323)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
(304)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Projected benefit obligation at 8,202us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
5,900us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
5,954us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Fair value of plan assets 0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
0us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Under funded status (8,202)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
(5,900)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
(5,954)us-gaap_DefinedBenefitPlanFundedStatusOfPlan
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Unamortized prior service cost 559us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
603us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
0us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Unrecognized actuarial gain 3,962us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
1,653us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
2,329us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Net amount recognized $ (3,681)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
$ (3,644)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember
$ (3,625)us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_DefinedBenefitPostretirementHealthCoverageMember