Supplemental Cash Flow Information - Details of Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash paid during the period for:
Income taxes, net	$ 25,395	$ 52,565	$ 14,789
Interest, net	1,609	1,048	800
Non-Cash Transaction Information:
Shares tendered in payment of exercise price of stock options	0	84	0
Employee stock purchase plan	578	699	613
Equipment acquired under capital leases	1,470	313	1,929
Unsettled repurchases of common stock	1,012	1,425	0
Contingent consideration for acquisition	$ 0	$ 477	$ 0