Acquisitions - Other Acquisitions (Details) - USD ($) $ in Millions			3 Months Ended
	Dec. 31, 2021	Dec. 01, 2021	Mar. 31, 2021
MEP Holdings
Acquisitions
Total purchase price	$ 57.3
Purchase price paid in cash	45.2
Promissory note payable	7.6
Mechanical Contractor Kentucky
Acquisitions
Total purchase price	20.6
Mechanical Contractor Indiana
Acquisitions
Total purchase price	$ 4.7
Ivey
Acquisitions
Total purchase price		$ 79.1
Purchase price paid in cash		64.1
Promissory note payable		8.0
Other amount payable		$ 0.4
Mechanical Contractor Utah
Acquisitions
Total purchase price			$ 18.1