Goodwill and Other Intangible Assets - Gross Carrying Amounts and Accumulated Amortization Relating to Other Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,942,125	$ 1,821,381
Accumulated Amortization	(443,868)	(329,284)
Net	1,498,257	1,492,097	$ 1,327,898
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,578,153	1,481,470
Accumulated Amortization	(388,120)	(287,851)
Net	1,190,033	1,193,619
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	358,253	334,643
Accumulated Amortization	(50,227)	(36,501)
Net	308,026	298,142
Non-competition agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,719	5,268
Accumulated Amortization	(5,521)	(4,932)
Net	$ 198	$ 336