Selected Quarterly Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information:
Revenue	$ 199,610		$ 182,802		$ 188,996		$ 178,858		$ 204,355	$ 162,403	$ 162,019	$ 153,918	$ 750,266	$ 682,695	$ 590,004
Gross profit	137,401		122,365		128,896		122,348		151,190	106,962	107,238	103,859	511,010	469,249	404,910
Income from operations	11,776		5,498		6,360		14,125		36,791	10,711	5,250	11,909	37,759	64,661	51,539
Income before provision for income taxes	10,696		5,515		5,498		13,493		36,498	10,246	4,501	9,260	35,202	60,505	47,994
Net income	$ 8,749		$ 3,301		$ 4,536		$ 10,400		$ 20,958	$ 6,325	$ 3,104	$ 5,935	$ 26,986	$ 36,322	$ 33,255
Net earnings per share, basic	$ 0.11		$ 0.04		$ 0.06		$ 0.14		$ 0.27	$ 0.08	$ 0.04	$ 0.08	$ 0.35	$ 0.47	$ 0.44
Net earnings per share, diluted	$ 0.11		$ 0.04		$ 0.06		$ 0.13		$ 0.26	$ 0.08	$ 0.04	$ 0.08	$ 0.34	$ 0.46	$ 0.42

[1] The Company elected to early adopt ASU 2016-09 in the fourth quarter of 2016, which requires, among other things, excess tax benefits to be recorded as a reduction of the provision for income taxes in the consolidated statement of operations, whereas they were previously recognized in equity. The Company is required to reflect any adoption adjustments as of January 1, 2016, the beginning of the annual period that includes the period of adoption. As such, certain information above includes the impact of the ASU 2016-09 adoption. See Note 2 "Significant Accounting Policies-New accounting pronouncements" for additional information related to this adoption.