Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Cash Flows [Abstract]
Net cash flows used in operating activities	$ (5,489)	$ (5,039)
Cash flows from investing activities:
Purchases of property, plant and equipment	(3,126)	(562)
Proceeds from the sale of property, plant and equipment	0	7
Purchase of Åkers, net of cash acquired (Note 2)	0	(27,031)
Purchases of long-term marketable securities	(20)	(246)
Proceeds from the sale of long-term marketable securities	85	193
Net cash flows used in investing activities	(3,061)	(27,639)
Cash flows from financing activities:
Dividends paid	(1,104)	(1,879)
Repayment of debt	(932)	0
Proceeds from credit facility	8,795	0
Payments on credit facility	(15,941)	0
Net cash flows used in financing activities	(9,182)	(1,879)
Effect of exchange rate changes on cash and cash equivalents	174	(424)
Net decrease in cash and cash equivalents	(17,558)	(34,981)
Cash and cash equivalents at beginning of period	38,579	95,122
Cash and cash equivalents at end of period	21,021	60,141
Supplemental information:
Income tax payments	202	3,000
Interest payments	721	61
Non-cash investing activities:
Purchases of property, plant and equipment included in accounts payable	344	152
Non-cash financing activities:
Issuance of common stock to acquire net assets of Åkers (Note 2)	0	22,137
Issuance of debt to acquire net assets of Åkers (Note 2)	$ 0	$ 25,710