CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Cash flows from operating activities:
Net income		$ 4,551	$ 1,798	$ 7,741	$ 2,223
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Depreciation and amortization				2,207	2,250
Amortization of marketable securities premium				81	75
Impairment charge on equity investee					313
Stock-based compensation				931	622
Realized gain on sale of available-for-sale securities					(77)
Gain on disposal of equipment				(13)	(1)
Loss from equity method investments, net				27	808
Changes in operating assets and liabilities:
Accounts receivable				61	(3,683)
Inventories				(11,923)	(119)
Prepaid expenses and other current assets				(2,075)	(264)
Other assets				59	(28)
Accounts payable				2,833	1,368
Accrued liabilities	[1]			(414)	21
Other long-term liabilities, including royalties				24	(302)
Net cash (used in) provided by operating activities				(461)	3,206
Cash flows from investing activities:
Purchases of property, plant and equipment				(21,920)	(1,831)
Proceeds from sale of equipment				11
Purchases of available-for-sale securities				(9,936)	(23,763)
Proceeds from sales and maturities of available-for-sale securities				17,870	10,170
Repayment of related party notes receivable					53
Net cash used in investing activities				(13,975)	(15,371)
Cash flows from financing activities:
Proceeds from issuance of common stock and options exercised, net of issuance costs				178	32,746
Considerations paid in cash to repurchase subsidiary shares from noncontrolling interest				(163)
Dividends paid by joint ventures to their minority shareholders					(465)
Net cash provided by financing activities				15	32,281
Effect of exchange rate changes on cash and cash equivalents				(233)	215
Net increase (decrease) in cash and cash equivalents				(14,654)	20,331
Cash and cash equivalents at the beginning of the period				44,352	36,152	$ 36,152
Cash and cash equivalents at the end of the period		$ 29,698	$ 56,483	29,698	$ 56,483	$ 44,352
Supplemental disclosure of non-cash flow information:
Consideration payable to repurchase subsidiary shares from noncontrolling interests, included in accrued liabilities				1,192
Reduction of noncontrolling interests in excess of total consideration paid and payable in connection with the repurchase of subsidiaries shares from noncontrolling interests				$ 196

[1] * Dividend accrued but not paid by one of our consolidated subsidiaries of $524 and $512 was included in accrued liabilities as of June 30, 2018 and 2017, respectively.