Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Net sales	$ 229,973	$ 216,665	$ 429,496	$ 393,156
Cost of sales	118,486	118,347	225,486	217,340
Gross profit	111,487	98,318	204,010	175,816
Operating expenses:
Research and development and other engineering	11,452	10,517	22,875	20,713
Selling	24,822	23,013	50,009	45,620
General and administrative	34,945	29,794	64,243	58,227
Net gain on disposal of assets	(656)	(15)	(682)	(30)
Total operating expenses	70,563	63,309	136,445	124,530
Income from operations	40,924	35,009	67,565	51,286
Interest expense, net	(83)	(54)	(318)	(89)
Income before taxes	40,841	34,955	67,247	51,197
Provision for income taxes	14,640	13,446	24,703	19,637
Net income	$ 26,201	$ 21,509	$ 42,544	$ 31,560
Earnings per common share:
Basic (in dollars per share)	$ 0.54	$ 0.44	$ 0.88	$ 0.64
Diluted (in dollars per share)	$ 0.54	$ 0.43	$ 0.88	$ 0.64
Number of shares outstanding
Basic (in shares)	48,399	49,254	48,353	49,236
Diluted (in shares)	48,605	49,473	48,533	49,445
Cash dividends declared per common share (in dollars per share)	$ 0.18	$ 0.16	$ 0.34	$ 0.3

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use; (3) to conduct internal product testing; (4) or to provide engineering support to customers in the form of testing services or product uses, specifications or requirements.

No definition available.