Goodwill and Intangibles - Schedule of Gross Carrying Amount and Accumulated Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 292,305	$ 270,091
Accumulated Amortization	136,907	116,529
Net Book Value	155,398	153,562
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	184,562	169,334
Accumulated Amortization	83,719	69,388
Net Book Value	100,843	99,946
Covenants Not-to-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	18,944	16,959
Accumulated Amortization	12,761	10,617
Net Book Value	6,183	6,342
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	73,543	69,718
Accumulated Amortization	26,042	22,609
Net Book Value	47,501	47,109
Backlog [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	15,256	14,080
Accumulated Amortization	14,385	13,915
Net Book Value	$ 871	$ 165