XML 123 R66.htm IDEA: XBRL DOCUMENT v2.4.1.9

Goodwill and Related Intangible Assets (Schedule of Acquired Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	84,524us-gaap_FiniteLivedIntangibleAssetsGross	$ 86,117us-gaap_FiniteLivedIntangibleAssetsGross
Total acquired intangible assets, Gross Carrying Amount	127,244rock_AcquiredIntangibleAssetsTotal	131,841rock_AcquiredIntangibleAssetsTotal
Accumulated Amortization, Finite-lived intangible assets	45,029us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization	40,064us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Total acquired intangible assets, Accumulated Amortization	45,029rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization	40,064rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	3,886us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	3,989us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Accumulated Amortization, Finite-lived intangible assets	1,827us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	1,420us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Unpatented technology and patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	24,527us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_UnpatentedTechnologyMember	24,690us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_UnpatentedTechnologyMember
Accumulated Amortization, Finite-lived intangible assets	8,768us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_UnpatentedTechnologyMember	6,980us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_UnpatentedTechnologyMember
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	52,974us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember	54,171us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Accumulated Amortization, Finite-lived intangible assets	31,554us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember	28,926us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_CustomerRelationshipsMember
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	1,807us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_NoncompeteAgreementsMember	1,937us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_NoncompeteAgreementsMember
Accumulated Amortization, Finite-lived intangible assets	1,550us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_NoncompeteAgreementsMember	1,408us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_NoncompeteAgreementsMember
Backlog
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Finite-lived intangible assets	1,330us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember	1,330us-gaap_FiniteLivedIntangibleAssetsGross / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember
Accumulated Amortization, Finite-lived intangible assets	1,330us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember	1,330us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_OrderOrProductionBacklogMember
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite-lived intangible assets	42,720us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	45,724us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Accumulated Amortization, Indefinite-lived intangible assets	0rock_IndefiniteLivedAccumulatedAmortization / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember	$ 0rock_IndefiniteLivedAccumulatedAmortization / us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis = us-gaap_TrademarksMember
Minimum | Trademarks
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	2 years
Minimum | Unpatented technology and patents
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years
Minimum | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years
Minimum | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	4 years
Minimum | Backlog
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	1 year
Maximum | Trademarks
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	15 years
Maximum | Unpatented technology and patents
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	20 years
Maximum | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	16 years
Maximum | Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	10 years
Maximum | Backlog
Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	2 years

X

- Definition

Acquired Intangible Assets, Total.

+ References

No definition available.

+ Details

Name:	rock_AcquiredIntangibleAssetsTotal
Namespace Prefix:	rock_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Indefinite-lived accumulated amortization.

+ References

No definition available.

+ Details

Name:	rock_IndefiniteLivedAccumulatedAmortization
Namespace Prefix:	rock_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Total acquired intangible assets, accumulated amortization

+ References

No definition available.

+ Details

Name:	rock_TotalAcquiredIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	rock_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OrderOrProductionBacklogMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TrademarksMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_UnpatentedTechnologyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TrademarksMember
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: