CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
Net sales	$ 271,053	$ 242,536	$ 768,201	$ 704,794
Material costs	79,401	73,109	226,585	212,706
Personnel costs	94,768	84,135	277,897	248,723
Other operating expenses	47,754	41,210	136,434	125,099
Depreciation and amortization	9,224	8,709	28,019	25,432
Income from operations	39,906	35,373	99,266	92,834
Interest expense	6,017	7,751	21,502	23,212
Extinguishment of debt			6,645
Income before taxes	33,889	27,622	71,119	69,622
Provision for income taxes	12,230	10,278	25,891	26,257
Net income	21,659	17,344	45,228	43,365
Comprehensive income	$ 21,659	$ 17,344	$ 45,228	$ 43,365
Basic Per Common Share Data
Net income (in dollars per share)	$ 0.62	$ 0.50	$ 1.30	$ 1.27
Shares used to compute basic per common share amounts (in shares)	34,902,103	34,362,757	34,783,419	34,224,756
Diluted Per Common Share Data
Net income (in dollars per share)	$ 0.61	$ 0.50	$ 1.28	$ 1.25
Shares used to compute diluted per common share amounts (in shares)	35,401,273	35,002,351	35,315,897	34,817,680