CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 35,469	$ 26,143	$ 19,311
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	13,736	9,158	7,849
Loss on disposal of fixed assets	104	17	35
Share–based compensation expense	6,970	5,468	5,651
Deferred income tax expense (benefit)	448	(728)	(248)
Other charges	2	67	22
Changes in operating assets and liabilities:
Receivables	825	(6,179)	(4,468)
Inventories	(7,974)	(3,631)	(811)
Other assets	76	(2,972)	(932)
Accounts payable	(5,356)	4,336	4,688
Accrued payroll and related benefits	2,795	1,006	(173)
Deferred revenue	1,864	1,194	196
Income taxes	1,297	(1,873)	3,051
Other accrued expenses and liabilities	342	(834)	(1,364)
Net cash provided by operating activities	50,598	31,172	32,807
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of short term investments	(19,127)	(16,811)	(8,225)
Proceeds from sales of short term investments	4,537	24,030	8,121
Capital additions	(14,756)	(12,986)	(8,265)
Cash paid for acquisition of a business	0	(15,000)	0
Net cash used in investing activities	(29,346)	(20,767)	(8,369)
CASH FLOWS FROM FINANCING ACTIVITIES:
Exercise of stock options	2,760	3,182	314
Employee tax withholdings related to the vesting of equity awards	(2,657)	(2,610)	(1,476)
Excess tax benefits from share-based compensation	2,938	3,122	(58)
Payment of dividends	(20,861)	(20,504)	(20,370)
Debt issuance costs	0	(24)	0
Net cash used in financing activities	(17,820)	(16,834)	(21,590)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	3,432	(6,429)	2,848
CASH AND CASH EQUIVALENTS, beginning of year	6,191	12,620	9,772
CASH AND CASH EQUIVALENTS, end of year	$ 9,623	$ 6,191	$ 12,620