XML 57 R39.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Employee Retirement Plans (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Defined Benefit Plan [Abstract] |
Schedule of Funded Status | The following table presents the changes in the plan’s projected benefit obligation, fair value of plan assets, and funded status for the years ended December 31 (in thousands):
| 2017 |  | 2016
Projected benefit obligation at January 1 | $ | 1,377 |  |  | $ | 1,685 |
Interest cost | 46 |  |  | 59 |
Actuarial losses (gains) | 7 |  |  | 5 |
Benefits paid | (360 | ) |  | (372 | )
Projected benefit obligation at December 31 | 1,070 |  |  | 1,377 |
Fair value of plan assets | — |  |  | — |
Under funded status | (1,070 | ) |  | (1,377 | )
Unamortized prior service cost | 2 |  |  | 4 |
Unrecognized actuarial gain | (173 | ) |  | (200 | )
Net amount recognized | $ | (1,241 | ) |  | $ | (1,573 | )
Schedule of Defined Benefit Plan, Amounts Recognized in Consolidated Financial Statements | Amounts recognized in the consolidated financial statements consisted of (in thousands):
| 2017 |  | 2016
Accrued pension liability: |  |  |
Current portion | $ | 327 |  |  | $ | 360 |
Long term portion | 743 |  |  | 1,016 |
Pre-tax accumulated other comprehensive income – retirement benefit liability adjustment | 171 |  |  | 197 |
Net amount recognized | $ | 1,241 |  |  | $ | 1,573 |
Components of Net Periodic Pension and Other Post-Retirement Benefit Costs Charged to Expense | Components of net periodic pension cost for the years ended December 31 were as follows (in thousands):
| 2017 |  | 2016 |  | 2015
Interest cost | $ | 46 |  |  | $ | 59 |  |  | $ | 66 |
Amortization of unrecognized prior service cost | 2 |  |  | 6 |  |  | 14 |
Gain amortization | (19 | ) |  | (13 | ) |  | — |
Net periodic pension cost | $ | 29 |  |  | $ | 52 |  |  | $ | 80 |
Assumptions used to calculate the benefit obligation: |  |  |  |  |
Discount rate | 3.55 | % |  | 3.81 | % |  | 3.94 | %
Schedule of Expected Benefit Payments | Expected benefit payments from the plan for the years ended December 31 are as follows (in thousands):
|  | 2018 |  | 2019 |  | 2020 |  | 2021 |  | 2022 |  | 2023 - 2027
Expected benefit payments |  | $ | 327 |  |  | $ | 228 |  |  | $ | 137 |  |  | $ | 100 |  |  | $ | 100 |  |  | $ | 292 |
Schedule of Multiemployer Plans | The Company’s participation in these plans for the year ended December 31, 2017 is outlined in the table below. The “EIN/ Pension Plan Number” column provides the Employee Identification Number (EIN) and three-digit plan number, if applicable. Unless otherwise noted, the most recent Pension Protection Act (PPA) zone status available in 2017 and 2016 is for the plan’s year ended December 31, 2016 and 2015, respectively. The zone status is based on information that the Company received from the plans and is certified by the plans’ actuaries. Among other factors, plans in the red zone are generally less than 65% funded, plans in the yellow zone are less than 80% funded, and plans in the green zone are at least 80% funded.
| EIN/ Pension |  | PPA Zone Status |  | Surcharge
Pension Fund | Plan Number |  | 2016 |  | 2015 |  | Imposed
National Integrated Group Pension Plan | 22-6190618-001 |  | Red |  | Red |  | Yes
Sheet Metal Workers’ National Pension Plan | 52-6112463-001 |  | Yellow |  | Yellow |  | Yes
Sheet Metal Workers’ Pension Plan of Northern California | 51-6115939-001 |  | Red |  | Red |  | Yes
Schedule of Contributions Made by the Company to Each Multiemployer Plan | The table below sets forth the contributions made by the Company to each multiemployer plan for the years ended December 31 (in thousands):
Pension Fund | 2017 |  | 2016 |  | 2015
National Integrated Group Pension Plan | $ | 220 |  |  | $ | 218 |  |  | $ | 246 |
Sheet Metal Workers’ National Pension Plan | 42 |  |  | 50 |  |  | 56 |
Sheet Metal Workers’ Pension Plan of Northern California | 30 |  |  | 28 |  |  | 31 |
| $ | 292 |  |  | $ | 296 |  |  | $ | 333 |
Schedule of Total Expense for All Retirement Plans | Total expense for all retirement plans for the years ended December 31 was (in thousands):
2017 |  | 2016 |  | 2015
$ | 3,044 |  |  | $ | 2,887 |  |  | $ | 2,934 |

X
- Definition Schedule Of Contributions Made By The Company To Each Multiemployer Plan [Table Text Block] + References No definition available. + Details
Name: | rock_ScheduleOfContributionsMadeByCompanyToEachMultiemployerPlanTableTextBlock
Namespace Prefix: | rock_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Defined Benefit Plan, Amounts Recognized In Consolidated Financial Statements [Table Text Block] + References No definition available. + Details
Name: | rock_ScheduleOfDefinedBenefitPlanAmountsRecognizedInConsolidatedFinancialStatementsTableTextBlock
Namespace Prefix: | rock_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DefinedBenefitPensionPlansAndDefinedBenefitPostretirementPlansDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the costs related to the various types of retirement plans including defined benefit pension plan cost, defined contribution plan cost, other postretirement benefit plan cost, and net periodic benefit cost. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfCostsOfRetirementPlansTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of benefits expected to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the quantitative and qualitative information related to multiemployer plans in which the employer participates. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
Name: | us-gaap_ScheduleOfMultiemployerPlansTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfNetBenefitCostsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of net funded status of pension plans and/or other employee benefit plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfNetFundedStatusTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration