Segment Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment location	Sep. 30, 2018 USD ($)
Segment Information
Number of reportable segments \| segment			2
Number or operating locations \| location			35
Revenues	$ 706,918	$ 594,536	$ 1,895,693	$ 1,594,520
Gross profit	142,702	127,868	369,383	328,104
Operating \| Mechanical Services
Segment Information
Revenues	590,016	592,925	1,677,632	1,592,909
Gross profit	128,501	127,669	344,632	327,905
Operating \| Electrical Services
Segment Information
Revenues	116,902	1,611	218,061	1,611
Gross profit	$ 14,201	$ 199	$ 24,751	$ 199

The number of operating locations.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

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-Name Accounting Standards Codification
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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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

No definition available.

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