Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Balance at beginning of period	$ 1,036,258	$ 828,051	$ 655,018
Acquisitions and adjustments	736	208,787	173,033
Divestitures	0	(580)	0
Balance at end of period	$ 1,036,994	$ 1,036,258	$ 828,051