Goodwill and Identifiable Intangible Assets, Net (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in the carrying amount of goodwill
Balance at the beginning of period	$ 114,588	$ 107,093
Additions		7,495
Impairment of goodwill	0	0	57,354
Balance at the end of period	114,588	114,588	107,093
Virginia, Maryland and North Carolina markets
Changes in the carrying amount of goodwill
Impairment of goodwill			$ 57,300
Number of reporting units, which could no longer support the related goodwill balance			4
Income valuation approach using discounted cash flow model
Changes in the carrying amount of goodwill
Weighting percentage		50.00%	50.00%
Public company market approach
Changes in the carrying amount of goodwill
Weighting percentage		40.00%	50.00%
Weight assigned to the public company approach for impacted reporting units, percentage		50.00%
Transaction approach
Changes in the carrying amount of goodwill
Weighting percentage		10.00%
Weight assigned to the transaction approach due to the lack of comparable market data, percentage		0.00%	0.00%

Represents the weighting percentage assigned to valuation approach.

No definition available.

Name:	fix_FairValueAssumptionWeightPercentageAssigned
Namespace Prefix:	fix_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of weight assigned to transaction approach due to the lack of comparable market data.

+ References

No definition available.

+ Details

Name:	fix_FairValueAssumptionWeightPercentageAssignedDueToLackOfComparableMarketData
Namespace Prefix:	fix_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of weight assigned to valuation approach for impacted reporting units.

+ References

No definition available.

+ Details

Name:	fix_FairValueAssumptionWeightPercentageAssignedForImpactedReportingUnits
Namespace Prefix:	fix_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of reporting units serving the markets, which could no longer support the related goodwill balance based on market activity declines and write-downs incurred on several jobs.

+ References

No definition available.

+ Details

Name:	fix_NumberOfReportingUnitsUnableToSupportRelatedGoodwillBalance
Namespace Prefix:	fix_
Data Type:	xbrli:integerItemType
Balance Type:	na
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/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

+ Details

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

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of loss from the write-down of an asset representing the 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/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13854-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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