CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues	$ 94,861	$ 127,922	$ 194,034	$ 247,150
Cost and expenses:
Cost of sales:	69,443	87,549	137,193	169,989
Selling, general and administrative	23,739	31,267	51,794	57,075
Engineering and product development	10,526	10,308	19,974	22,158
Gain on sale of assets	(5,099)	(88)	(5,099)	(88)
Total costs and expenses	98,609	129,036	203,862	249,134
Operating loss	(3,748)	(1,114)	(9,828)	(1,984)
Interest income	2,275	1,070	4,075	2,007
Interest expense	(151)	(18)	(350)	(33)
Income (loss) before income taxes	(1,624)	(62)	(6,103)	(10)
Income tax provision (benefit)	1,418	(77)	4,318	(120)
Net income (loss)	$ (3,042)	$ 15	$ (10,421)	$ 110
Earnings (loss) per common share:
Basic (in dollars per share)	$ (0.08)	$ 0.00	$ (0.28)	$ 0.00
Diluted (in dollars per share)	$ (0.08)	$ 0.00	$ (0.28)	$ 0.00
Weighted average common shares outstanding:
Basic (in shares)	37,615	37,528	37,672	37,526
Diluted (in shares)	37,615	37,718	37,672	37,706
Products
Revenues	$ 64,719	$ 102,092	$ 135,764	$ 193,684
Cost and expenses:
Cost of sales:	51,822	74,991	103,431	141,453
Services
Revenues	30,142	25,830	58,270	53,466
Cost and expenses:
Cost of sales:	$ 17,621	$ 12,558	$ 33,762	$ 28,536