Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Cash Flows [Abstract]
Net cash flows provided by (used in) operating activities - continuing operations	$ 12,605	$ (7,089)
Cash flows from investing activities:
Purchases of property, plant and equipment	(1,912)	(1,379)
Purchases of long-term marketable securities	(2)	(12)
Proceeds from sale of long-term marketable securities	71	80
Net cash flows used in investing activities - continuing operations	(1,843)	(1,311)
Cash flows from financing activities:
Repayment of debt	(335)	(27,080)
Proceeds from Revolving Credit and Security Agreement	853	29,217
Payments on Revolving Credit and Security Agreement	(3,662)	(3,500)
Funding of discontinued operations	0	573
Net cash flows used in financing activities - continuing operations	(3,144)	(790)
Effect of exchange rate changes on cash and cash equivalents	(636)	(80)
Cash flows from discontinued operations:
Net cash flows provided by operating activities - discontinued operations	0	108
Net cash flows used in investing activities - discontinued operations	0	(264)
Net cash flows used in financing activities - discontinued operations	0	(573)
Net cash flows used in discontinued operations	0	(729)
Net increase (decrease) in cash and cash equivalents	6,982	(9,999)
Cash and cash equivalents at beginning of period	6,960	20,837
Cash and cash equivalents at end of period	13,942	10,838
Less: cash and cash equivalents of discontinued operations	0	(395)
Cash and cash equivalents of continuing operations at end of period	13,942	10,443
Supplemental information:
Income tax payments	312	212
Interest payments	874	370
Non-cash investing and financing activities:
Purchases of property, plant and equipment included in accounts payable	878	780
Finance lease right-of-use assets exchanged for lease liabilities	382	453
Operating lease right-of-use assets exchanged for lease liabilities	$ 610	$ 0