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:
Income from continuing operations	$ 27,625	$ 35,101	$ 26,803
Loss from discontinued operations	(1,358)	(923)	(201)
Net income	26,267	34,178	26,602
Adjustments to reconcile net income to net cash provided by operating activities:
Asset impairment charge	8,800	0	0
Depreciation and amortization	8,643	7,874	3,412
Bad debt expense	311	289	786
Inventory lower-of-cost-or-market/NRV adjustments	1,067	245	1,583
Stock-based compensation expense	1,856	2,613	1,484
Loss on asset disposals	56	147	313
Deferred income taxes, net of valuation allowances	(8,556)	9,510	11,669
Excess tax benefit related to stock-based awards	0	(1,857)	(28)
Other	(117)	5	0
Changes in operating assets and liabilities:
Trade receivables	2,516	(694)	(6,812)
Inventories	(7,526)	(3,110)	(7,147)
Prepaids and other current assets	1,080	(1,415)	1,365
Income taxes receivable	3,214	(2,792)	(389)
Trade payables	449	6,464	4,506
Accrued liabilities, including warranty obligations	(3,044)	(5,606)	3,776
Net cash provided by operating activities	35,016	45,851	41,120
Cash flows from investing activities:
Acquisition of business, net of cash acquired	0	(3,468)	(114,062)
Purchases of property, plant and equipment and intangible assets	(3,792)	(4,656)	(5,734)
Purchases of available-for-sale-securities	(88,413)	(34,739)	(61,933)
Proceeds from maturities of available-for-sale securities	62,939	32,923	55,292
Proceeds from sales of available-for-sale securities	0	71	3,602
Net cash used in investing activities	(29,266)	(9,869)	(122,835)
Cash flows from financing activities:
Proceeds from long-term debt	0	0	80,000
Proceeds from employee stock purchases	16,000	16,000	0
Proceeds from employee stock purchases	487	381	116
Tax payments related to stock award issuances	560	356	1,050
Excess tax benefit related to stock-based awards	(741)	(239)	(775)
Excess tax benefit related to stock-based awards	0	1,857	28
Payments for stock repurchases	(11,055)	(5,390)	(11,567)
Net cash provided by (used in) financing activities	(26,749)	(19,035)	68,852
Effect of exchange rate changes on cash and cash equivalents	1,018	149	(1,565)
Increase (decrease) in cash and cash equivalents	(19,981)	17,096	(14,428)
Beginning of year	47,874	30,778	45,206
End of year	27,893	47,874	30,778
Supplemental disclosure of cash flow information:
Cash paid for income taxes, net	11,630	11,511	1,308
Cash paid for interest	1,545	1,920	22
Acquisition consideration owed but not yet paid	0	0	2,813
Capital expenditures incurred but not yet paid	404	210	1,000
Loan fees incurred but not yet paid	$ 0	$ 0	$ 36