Fair Value, Measurement Period

No definition available.

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Namespace Prefix:	rock_
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Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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+ Details

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Period Type:	duration

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

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

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_SellingGeneralAndAdministrativeExpensesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=rock_QualityAluminumProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Acquisition (Narrative) (Details) - USD ($)		3 Months Ended		6 Months Ended
Acquisition (Narrative) (Details) - USD ($)	Aug. 22, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Business Acquisition [Line Items]
Goodwill		$ 511,961,000		$ 511,961,000		$ 512,363,000
Selling, General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Acquisition related costs		$ 0	$ 0	$ 21,000	$ 7,000
Quality Aluminum Products
Business Acquisition [Line Items]
Acquisition purchase price	$ 52,100,000
Measurement period				1 year
Goodwill	$ 3,991,000