Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income (loss)	$ 6,223	$ 3,056	$ (2,809)
Adjustments to reconcile net income (loss) to net cash from operating activities
Depreciation and amortization	20,124	20,841	20,923
Amortization of debt costs and other assets	1,712	1,569	1,752
Provision for doubtful accounts	1,639	1,117	3,431
Deferred income taxes	21,286	10,460	(1,156)
Share-based compensation	12,557	15,966	7,214
Gain on sale of assets			(3,099)
Other-than-temporary impairment on debt securities	5,585	2,727
Other	1,398	1,061	2,854
Changes in operating assets and liabilities
Restricted cash	14,369	(14,369)
Trade accounts receivable	(6,562)	392	(1,547)
Inventories	(15,645)	(5,284)	3,136
Prepaid expenses and other current assets	(6,352)	701	8,697
Other long-term assets	1,490	(3,333)	(1,321)
Trade accounts payable	2,324	(1,771)	3,011
Other current liabilities	(11,412)	6,537	1,515
Other long-term liabilities	4,605	5,037	1,009
Net cash from operating activities	53,341	44,707	43,610
Cash flows from investing activities
Capital expenditures for property, plant and equipment	(14,665)	(16,432)	(27,197)
Capital expenditures for intangible assets	(2,283)	(1,902)	(702)
Purchase of debt securities			(15,250)
Proceeds from sale of assets			4,800
Net cash from investing activities	(16,474)	(21,947)	(38,349)
Other investing activities	474	(3,613)
Cash flows from financing activities
Proceeds from issuance of common shares	7,783	19,720	5,254
Payments related to withholdings for share-based compensation	(3,800)	(2,407)	(1,550)
Payment of debt issuance costs	(445)		(1,825)
Changes in restricted cash			34,424
Repurchase and retirement of common shares		(63,425)	(11,575)
Net cash from financing activities	3,538	(46,112)	24,728
Effect of exchange rate changes on cash	1,180	(739)	(3,141)
Net change in cash and cash equivalents	41,585	(24,091)	26,848
Cash and cash equivalents at the beginning of the year	39,572	63,663	36,815
Cash and cash equivalents at the end of the year	81,157	39,572	63,663
Cash paid during the year for:
Interest	811	672	852
Income taxes	$ 3,265	$ 4,423	$ 3,160