Goodwill and Other Intangible Assets - Components of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	$ 379,808	$ 373,117	$ 327,050	$ 320,761
Other intangible assets (net of accumulated amortization)	8,100	8,907
Goodwill and other intangible assets, Total	$ 387,908	$ 382,024