Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Revenues	$ 820,119	$ 946,548	$ 747,763
Cost of revenues
Cost of revenues	684,738	766,975	607,899
Selling, general and administrative expenses	113,394	115,127	108,838
Other operating (income) loss, net	170	888	(410)
Goodwill impairment	11,422	0	0
Operating income	10,395	63,558	31,436
Foreign currency exchange (gain) loss	(816)	1,416	2,051
Interest expense, net	14,369	14,864	13,273
Income (loss) from continuing operations before income taxes	(3,158)	47,278	16,112
Provision for income taxes	9,788	14,997	4,893
Income (loss) from continuing operations	(12,946)	32,281	11,219
Loss from disposal of discontinued operations, net of tax	0	0	(17,367)
Net income (loss)	$ (12,946)	$ 32,281	$ (6,148)
Income (loss) per common share - basic:
Income (loss) from continuing operations (in dollars per share)	$ (0.14)	$ 0.36	$ 0.13
Loss from discontinued operations (in dollars per share)	0	0	(0.20)
Net income (loss) (in dollars per share)	(0.14)	0.36	(0.07)
Income (loss) per common share - diluted:
Income (loss) from continuing operations (in dollars per share)	(0.14)	0.35	0.13
Loss from discontinued operations (in dollars per share)	0	0	(0.20)
Net income (loss) (in dollars per share)	$ (0.14)	$ 0.35	$ (0.07)
Product sales [Member]
Revenues
Revenues	$ 654,006	$ 743,342	$ 628,401
Cost of revenues
Cost of revenues	568,388	633,847	539,243
Rental and service [Member]
Revenues
Revenues	166,113	203,206	119,362
Cost of revenues
Cost of revenues	$ 116,350	$ 133,128	$ 68,656