CONSOLIDATED STATEMENTS OF INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Revenues from products and services	$ 375,297
Leasing	39,509	$ 47,160	$ 42,392
Total revenues	414,806	384,626	455,469
Cost of sales:
Total cost of sales	295,007	293,573	330,243
Selling, general and administrative	96,782	101,090	113,588
Engineering and product development	17,329	20,297	19,974
Impairment, restructuring and other charges	4,396	98,602	60,968
Gain on sale of assets	(1,511)	(6,198)	(168)
Total costs and expenses	412,003	507,364	524,605
Operating income (loss)	2,803	(122,738)	(69,136)
Interest income	7,940	8,040	3,564
Interest expense	(314)	(291)	(72)
Income (loss) before income taxes	10,429	(114,989)	(65,644)
Income tax provision (benefit)	8,709	(19,294)	34,995
Net income (loss)	$ 1,720	$ (95,695)	$ (100,639)
Income (loss) per common share:
Basic (in dollars per share)	$ 0.05	$ (2.58)	$ (2.69)
Diluted (in dollars per share)	$ 0.05	$ (2.58)	$ (2.69)
Weighted average common shares outstanding:
Basic (in shares)	35,839	37,075	37,457
Diluted (in shares)	36,152	37,075	37,457
Products
Revenues:
Revenues from products and services	$ 303,279	$ 265,052	$ 351,132
Cost of sales:
Total cost of sales	223,502	222,568	270,854
Services
Revenues:
Revenues from products and services	72,018	72,414	61,945
Cost of sales:
Total cost of sales	36,550	37,196	32,733
Leasing
Cost of sales:
Total cost of sales	$ 34,955	$ 33,809	$ 26,656