Amount of contingent earn-out payment under business combination.

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Amount of working capital settlement under business combination.

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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.

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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.

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Amount of liabilities incurred by the acquirer as part of consideration transferred in a business combination.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Acquisitions - Other Acquisitions (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
T E C Industrial Construction and Maintenance
Acquisitions
Total purchase price		$ 89.6
Purchase price paid in cash		73.0
Promissory note payable		7.0
Estimated fair value of contingent earn-out payments		7.6
Working capital adjustment		$ 2.0
Electrical Contractor North Carolina
Acquisitions
Total purchase price			$ 41.6
Mechanical Contractor Utah
Acquisitions
Total purchase price	$ 19.6