Quarterly Financial Information (Unaudited) - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 375,254	$ 351,014	$ 349,675	$ 326,038	$ 361,783	$ 331,096	$ 339,331	$ 325,894	$ 1,401,981	$ 1,358,104	$ 1,196,809
Gross profit	166,845	158,701	161,084	149,982	162,386	148,302	153,836	147,339	636,612	611,863	538,891
Net income	$ 31,163	$ 42,239	$ 39,806	$ 23,232	$ 24,883	$ 33,717	$ 33,179	$ 32,371	$ 136,440	$ 124,150	$ 26,027
Basic (dollars per share)	$ 0.80	$ 1.09	$ 1.03	$ 0.60	$ 0.65	$ 0.88	$ 0.86	$ 0.85	$ 3.52	$ 3.23	$ 0.68
Diluted (dollars per share)	$ 0.79	$ 1.08	$ 1.01	$ 0.59	$ 0.64	$ 0.86	$ 0.85	$ 0.83	$ 3.48	$ 3.18	$ 0.67