Number of collective bargaining agreements.

No definition available.

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- Definition

Number Of Employees

+ References

No definition available.

+ Details

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- Definition

Before tax amount of additional minimum pension liability not yet recognized as a net periodic pension cost.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i)

-URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (j)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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- Definition

The aggregate net amount recognized in the balance sheet associated with the defined benefit plan(s). Will normally be the same as the Defined Benefit Plan, Funded Status of Plan, Total.

+ 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=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=21915240&loc=d3e1703-114919

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- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ 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 (a)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Projected Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6522206

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Postretirement Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503904

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- Details

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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- Definition

Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan, in CCYY-MM-DD format. 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

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

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- Definition

Percentage of employee participants subject to a collective bargaining arrangement to all participants in 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

+ Details

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- Details

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- Details

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- Details

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Employee Retirement Plans (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 employee	Dec. 31, 2013 agreement	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 1,961	$ 2,179	$ 2,478	$ 2,653
Net liability	2,116	2,328	2,555
Number of employees	2,416rock_NumberOfEmployees
Employees represented by unions through CBAs, percentage	12.00%
Number of CBAs expired and successfully renegotiated		3
Company's maximum contribution percentage	5.00%	5.00%	5.00%
Sheet Metal Workers Pension Plan Of Northern California [Member]
Defined Benefit Plan Disclosure [Line Items]
CBAs expiration date	Jun. 05, 2015
Sheet Metal Workers National Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
CBAs expiration date	Apr. 30, 2015
National Integrated Group Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
CBAs expiration date	Apr. 15, 2015
Foreign Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	410	441
Pre-tax accumulated other comprehensive loss - retirement benefit liability adjustment	113	73
Net liability	$ 297	$ 368