Goodwill and Other Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 1,657,332	$ 1,659,500
Intangible assets, Accumulated Amortization	789,427	744,854
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	1,418,437	1,420,224
Intangible assets, Accumulated Amortization	677,547	641,089
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	176,089	176,471
Intangible assets, Accumulated Amortization	82,426	77,208
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	62,806	62,805
Intangible assets, Accumulated Amortization	$ 29,454	$ 26,557