Goodwill and Other Intangible Assets, Net - Components of Other Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	$ 298,172	$ 292,525
Accumulated Amortization	96,033	73,481
Net definite life intangible assets	$ 202,139	$ 219,044
Weighted-Average Remaining Life	11 years 3 months 18 days	11 years 10 months 24 days
Total indefinite life intangible assets	$ 91,841	$ 91,977
Total definite and indefinite life intangible assets, gross, excluding goodwill	390,013	384,502
Total definite and indefinite life intangible assets, net, excluding goodwill	293,980	311,021
Trade Names [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total indefinite life intangible assets	83,912	84,048
Licenses [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total indefinite life intangible assets	7,929	7,929
Customer-Related Intangible Assets [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	204,735	203,743
Accumulated Amortization	39,047	27,820
Net definite life intangible assets	$ 165,688	$ 175,923
Weighted-Average Remaining Life	12 years 10 months 24 days	13 years 8 months 12 days
Technology [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	$ 24,024	$ 24,025
Accumulated Amortization	12,326	9,741
Net definite life intangible assets	$ 11,698	$ 14,284
Weighted-Average Remaining Life	3 years 4 months 24 days	4 years 2 months 12 days
Noncompete Agreements [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	$ 36,535	$ 34,333
Accumulated Amortization	20,886	16,180
Net definite life intangible assets	$ 15,649	$ 18,153
Weighted-Average Remaining Life	2 years 4 months 24 days	2 years 8 months 12 days
Patents [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	$ 10,412	$ 10,629
Accumulated Amortization	10,272	10,049
Net definite life intangible assets	$ 140	$ 580
Weighted-Average Remaining Life	7 years 10 months 24 days	3 years 7 months 6 days
All Other [Member]
Schedule Of Acquired Finite And Indefinite Lived Intangible Asset By Major Class [Line Items]
Total gross definite life intangible assets	$ 22,466	$ 19,795
Accumulated Amortization	13,502	9,691
Net definite life intangible assets	$ 8,964	$ 10,104
Weighted-Average Remaining Life	7 years 9 months 18 days	9 years 2 months 12 days