Goodwill and Identifiable Intangible Assets, Net - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Changes in the carrying amount of goodwill
Balance at beginning of year	$ 592,114	$ 464,392
Acquisitions and purchase price adjustments (See Note 5)	18,925	127,722
Balance at end of period	611,039	592,114
Mechanical Services Segment
Changes in the carrying amount of goodwill
Balance at beginning of year	361,320	307,448
Acquisitions and purchase price adjustments (See Note 5)	1,859	52,771
Impact of segment reorganization		1,101
Balance at end of period	363,179	361,320
Electrical Services Industry
Changes in the carrying amount of goodwill
Balance at beginning of year	230,794	156,944
Acquisitions and purchase price adjustments (See Note 5)	17,066	74,951
Impact of segment reorganization		(1,101)
Balance at end of period	$ 247,860	$ 230,794