Summary of the Unaudited Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																								12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Quarterly Financial Information [Line Items]
Net sales	$ 543,711		$ 531,350		$ 514,831		$ 437,597		$ 527,477		$ 491,697		$ 486,021		$ 358,120		$ 458,354		$ 439,977		$ 413,126		$ 324,229		$ 2,027,489	$ 1,863,315	$ 1,635,686
Gross profit	87,819		86,022		72,405		57,197		62,721		61,628		61,613		46,672		52,587		61,497		58,853		42,186		303,443	232,634	215,123
Net income	$ 33,286		$ 31,880		$ 28,649		$ 10,474		$ 19,088		$ 18,307		$ 16,239		$ 7,296		$ 10,423		$ 16,236		$ 14,135		$ 5,735		$ 104,289	$ 60,930	$ 46,529
Basic net income per share (in dollars per share)	$ 0.50		$ 0.48		$ 0.42		$ 0.15		$ 0.28		$ 0.26		$ 0.23		$ 0.11		$ 0.15		$ 0.24		$ 0.20		$ 0.08		$ 1.55	$ 0.88	$ 0.67
Diluted net income per share (in dollars per share)	$ 0.50	[1]	$ 0.47	[1]	$ 0.41	[1]	$ 0.15	[1]	$ 0.27	[1]	$ 0.25	[1]	$ 0.23	[1]	$ 0.10	[1]	$ 0.15	[1]	$ 0.23	[1]	$ 0.20	[1]	$ 0.08	[1]	$ 1.50	$ 0.85	$ 0.67

[1] Basic and diluted net income per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly net income per share may differ from annual net income per share due to rounding.