CONSOLIDATED STATEMENTS OF INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues from products and services	$ 337,466
Leasing	47,160	$ 42,392	$ 41,625
Total revenues	384,626	455,469	538,731
Cost of sales:
Total cost of sales	271,499	305,394	328,404
Selling, general and administrative	104,039	116,251	53,246
Engineering and product development	39,422	42,160	44,325
Impairment, restructuring and other charges	98,602	60,968	0
Gain on sale of assets	(6,198)	(168)	(103)
Total costs and expenses	507,364	524,605	425,872
Operating income (loss)	(122,738)	(69,136)	112,859
Interest income	8,040	3,564	3,037
Interest expense	(291)	(72)	(28)
Income (loss) before income taxes	(114,989)	(65,644)	115,868
Income tax provision (benefit)	(19,294)	34,995	22,647
Net income (loss)	$ (95,695)	$ (100,639)	$ 93,221
Earnings (loss) per common share:
Basic (in dollars per share)	$ (2.58)	$ (2.69)	$ 2.48
Diluted (in dollars per share)	$ (2.58)	$ (2.69)	$ 2.47
Weighted average common shares outstanding:
Basic (in shares)	37,075	37,457	37,537
Diluted (in shares)	37,075	37,457	37,667
Products
Revenues:
Revenues from products and services	$ 265,052	$ 351,132	$ 433,012
Cost of sales:
Total cost of sales	200,494	246,005	268,405
Services
Revenues:
Revenues from products and services	72,414	61,945	64,094
Cost of sales:
Total cost of sales	62,109	53,303	52,611
Leasing
Cost of sales:
Total cost of sales	$ 8,896	$ 6,086	$ 7,388