Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 20,216	$ 15,080
Adjustments to reconcile net income to net cash used by operating activities:
Depreciation and amortization	7,013	6,411
Provision (credit) for doubtful accounts	(82)	436
Provision for warranties	3,453	3,996
Deferred compensation benefit	(166)	(376)
Stock-based compensation	903	1,017
Deferred income tax expense (benefit)	86	(372)
Gain on disposition of fixed assets	(48)	(133)
Distributions to SERP participants	(124)	(123)
Change in operating assets and liabilities:
Sale (purchase) of trading securities, net	(108)	406
Trade and other receivables	(33,744)	(45,910)
Inventories	(19,780)	(12,166)
Prepaid expenses and other assets	(3,098)	401
Accounts payable	9,293	16,276
Accrued payroll and related expenses	(3,929)	(7,687)
Accrued product warranty	(2,825)	(3,460)
Customer deposits	2,138	(154)
Prepaid and income taxes payable, net	6,468	8,249
Other	2,013	3,387
Net cash used by operating activities	(12,321)	(14,722)
Cash flows from investing activities:
Expenditures for property and equipment	(5,011)	(5,406)
Proceeds from sale of property and equipment	59	140
Other	(393)	(292)
Net cash used by investing activities	(5,345)	(5,558)
Cash flows from financing activities:
Payment of dividends	(2,308)	(2,306)
Repayments of bank loans	(643)	(4,601)
Sale of Company shares held by SERP	376	285
Withholding tax paid upon vesting of restricted stock units	(364)	(501)
Net cash used by financing activities	(2,939)	(7,123)
Effect of exchange rates on cash	265	433
Net decrease in cash and cash equivalents	(20,340)	(26,970)
Cash and cash equivalents, beginning of period	62,280	82,371
Cash and cash equivalents, end of period	$ 41,940	$ 55,401