XML 75 R72.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Debt (Narrative) (Details) (USD $) | 1 Months Ended | 12 Months Ended | 3 Months Ended | 1 Months Ended
--- | --- | --- | --- | ---
Jan. 31, 2014 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Mar. 31, 2013 | Jan. 31, 2013
Debt Instrument [Line Items] |  |  |  |  |  |
Standby letters of credit |  | $ 20,377,000 us-gaap_LettersOfCreditOutstandingAmount |  |  |  |
Paid placement and other fees |  | 35,000 us-gaap_PaymentsOfFinancingCosts | 3,899,000 us-gaap_PaymentsOfFinancingCosts | 18,000 us-gaap_PaymentsOfFinancingCosts |  |
Dividend payment restrictions, annual limit per share | $ 0.25 rock_DividendPaymentRestrictionsAnnualLimitsPerShare |  |  |  |  |
Dividend payment restrictions, aggregate annual limit | 25,000,000 rock_DividendPaymentRestrictionsAggregateAnnualLimits |  |  |  |  |
Senior Credit Agreement |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Current borrowing capacity |  | 200,000,000 us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity / us-gaap_DebtInstrumentAxis = rock_SeniorCreditAgreementMember |  |  |  |
Maximum borrowing capacity under the revolving credit facility |  | 250,000,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / us-gaap_DebtInstrumentAxis = rock_SeniorCreditAgreementMember |  |  |  |
Fixed charge coverage ratio |  | 125.00%rock_RevolvingCreditFacilityMinimumFixedChargeCoverageRatio / us-gaap_DebtInstrumentAxis = rock_SeniorCreditAgreementMember |  |  |  |
Senior Subordinated 8% Notes, Due December 1, 2015 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Interest rate |  |  |  |  |  | 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember
Repurchase amount |  |  |  |  |  | 204,000,000 us-gaap_DebtInstrumentRepurchaseAmount / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember
Repurchase charge |  |  |  |  | 7,166,000 us-gaap_GainLossOnRepurchaseOfDebtInstrument / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember |
Prepayment premium paid |  |  |  |  | 3,702,000 rock_DebtInstrumentPrepaymentPremium / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember |
Write off of deferred financing costs |  |  |  |  | 2,199,000 us-gaap_WriteOffOfDeferredDebtIssuanceCost / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember |
Unamortized original issue discount |  |  | 1,298,000 us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember |  | 1,265,000 us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember |
Senior Subordinated 6.25% Notes |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Notes issued |  |  |  |  |  | 210,000,000 us-gaap_NotesIssued1 / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember
Interest rate |  | 6.25%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember | 6.25%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember |  |  | 6.25%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember
Paid placement and other fees |  |  |  |  | 3,755,000 us-gaap_PaymentsOfFinancingCosts / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember |
Senior Subordinated 6.25% Notes | Change in Control |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Purchase price of the principal amount, percentage | 101.00%rock_PurchasePriceOfPrincipalAmountPercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = rock_ChangeInControlMember |  |  |  |  |
Senior Subordinated 6.25% Notes | On and After February 1, 2019 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price, percentage of principal amount | 100.00%us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = us-gaap_DebtInstrumentRedemptionPeriodThreeMember |  |  |  |  |
Senior Subordinated 6.25% Notes | Prior to February 1, 2016 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price, percentage of principal amount | 106.25%us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = us-gaap_DebtInstrumentRedemptionPeriodFourMember |  |  |  |  |
Redemption percentage of aggregate principal amount | 35.00%rock_DebtInstrumentRedemptionPercentageOfAggregatePrincipalAmount / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = us-gaap_DebtInstrumentRedemptionPeriodFourMember |  |  |  |  |
Revolving Credit Facility |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Annual commitment fee |  | 0.375%us-gaap_LineOfCreditFacilityCommitmentFeePercentage / us-gaap_DebtInstrumentAxis = us-gaap_RevolvingCreditFacilityMember |  |  |  |
Availability amount |  | $ 98,350,000 us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity / us-gaap_DebtInstrumentAxis = us-gaap_RevolvingCreditFacilityMember |  |  |  |
Minimum | Senior Subordinated 6.25% Notes | 12-Month Redemption Period Beginning February 1, 2018 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price percentage | 101.56%us-gaap_DebtInstrumentRedemptionPricePercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = rock_TwelveMonthRedemptionPeriodBeginningFebruaryOneTwoThousandEighteenMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |  |
Minimum | Revolving Credit Facility |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
LIBOR floor, plus |  | 2.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_DebtInstrumentAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |  |  |
Maximum | Senior Subordinated 6.25% Notes | 12-Month Redemption Period Beginning February 1, 2017 |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Redemption price percentage | 103.13%us-gaap_DebtInstrumentRedemptionPricePercentage / us-gaap_DebtInstrumentAxis = rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember / us-gaap_DebtInstrumentRedemptionPeriodAxis = rock_TwelveMonthRedemptionPeriodBeginningFebruaryOneTwoThousandSeventeenMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |  |
Maximum | Revolving Credit Facility |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
LIBOR floor, plus |  | 2.50%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 / us-gaap_DebtInstrumentAxis = us-gaap_RevolvingCreditFacilityMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |  |  |

X
- Definition Debt instrument prepayment premium. + References No definition available. + Details
Name: | rock_DebtInstrumentPrepaymentPremium
Namespace Prefix: | rock_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Debt instrument redemption percentage of aggregate principal amount. + References No definition available. + Details
Name: | rock_DebtInstrumentRedemptionPercentageOfAggregatePrincipalAmount
Namespace Prefix: | rock_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Dividend payment restrictions, aggregate annual limit. + References No definition available. + Details
Name: | rock_DividendPaymentRestrictionsAggregateAnnualLimits
Namespace Prefix: | rock_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Dividend payment restrictions, annual limits per share. + References No definition available. + Details
Name: | rock_DividendPaymentRestrictionsAnnualLimitsPerShare
Namespace Prefix: | rock_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase Price Of The Principal Amount, Percentage + References No definition available. + Details
Name: | rock_PurchasePriceOfPrincipalAmountPercentage
Namespace Prefix: | rock_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Revolving credit facility minimum fixed charge coverage ratio. + References No definition available. + Details
Name: | rock_RevolvingCreditFacilityMinimumFixedChargeCoverageRatio
Namespace Prefix: | rock_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Percentage price of original principal amount of debt at which debt can be redeemed by the issuer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph e -URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of principal amount of debt redeemed. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value amount of debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase. + References No definition available. + Details
Name: | us-gaap_GainLossOnRepurchaseOfDebtInstrument
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
Name: | us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value of notes issued in noncash investing and financing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586 + Details
Name: | us-gaap_NotesIssued1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow for loan and debt issuance costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfFinancingCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_WriteOffOfDeferredDebtIssuanceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=rock_SeniorCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=rock_SeniorSubordinatedEightPercentNotesDueDecemberOneTwoThousandFifteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=rock_SeniorSubordinatedSixPointTwoFivePercentNotesDueFebruaryOneTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |