CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME
Net sales	$ 273,735	$ 251,754	$ 507,270	$ 469,845
Material costs	79,446	72,899	147,184	139,597
Personnel costs	93,176	83,435	183,129	164,588
Other operating expenses	54,959	51,256	98,802	91,475
Depreciation and amortization	9,510	8,438	18,795	16,723
Income from operations	36,644	35,726	59,360	57,462
Interest expense	7,708	7,684	15,485	15,461
Extinguishment of debt	6,645		6,645
Income before taxes	22,291	28,042	37,230	42,001
Provision for income taxes	8,212	10,656	13,661	15,980
Net income	14,079	17,386	23,569	26,021
Comprehensive income	$ 14,079	$ 17,386	$ 23,569	$ 26,021
Basic Per Common Share Data
Net income (in dollars per share)	$ 0.40	$ 0.51	$ 0.68	$ 0.76
Shares used to compute basic per common share amounts (in shares)	34,849,659	34,268,941	34,724,077	34,110,820
Diluted Per Common Share Data
Net income (in dollars per share)	$ 0.40	$ 0.50	$ 0.67	$ 0.75
Shares used to compute diluted per common share amounts (in shares)	35,307,697	34,720,489	35,225,871	34,637,769