Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating Activities
Net income	$ 33,625	$ 29,781
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	8,660	9,349
Amortization of bond premiums	561	545
Provision for losses on accounts receivable, net of adjustments	(59)	121
Provision for excess and obsolete inventories, net	223	468
Share-based compensation	1,578	1,054
Excess tax benefits from stock options exercised and restricted stock awards vested	(908)	(502)
Gain on disposal of assets	(24)	(52)
Foreign currency transaction loss	36	35
Interest income on note receivable	(30)	(31)
Deferred income taxes	(4,361)	(1,794)
Write-off of note receivable	0	75
Changes in assets and liabilities:
Accounts receivable	(15,663)	(2,384)
Income tax receivable	1,981	1,753
Inventories	(5,323)	(1,237)
Prepaid expenses and other	(486)	121
Accounts payable	5,982	(227)
Deferred revenue	591	358
Accrued liabilities	12,761	1,410
Net cash provided by operating activities	39,144	38,843
Investing Activities
Capital expenditures	(13,567)	(6,407)
Proceeds from sale of property, plant and equipment	30	72
Investment in certificates of deposits	(9,940)	(8,869)
Maturities of certificates of deposits	6,745	1,440
Purchase of investments held to maturity	(6,880)	(22,275)
Maturities of investments	8,891	3,315
Proceeds from called investments	2,525	0
Principal payments from note receivable	52	52
Net cash used in investing activities	(12,144)	(32,672)
Financing Activities
Borrowings under revolving credit facility	0	8,325
Payments under revolving credit facility	0	(8,325)
Stock options exercised	908	986
Excess tax benefits from stock options exercised and restricted stock awards vested	908	502
Repurchase of stock	(17,309)	(4,817)
Cash dividends paid to stockholders	4,773	3,712
Net cash used in financing activities	(20,266)	(7,041)
Net increase (decrease) in cash and cash equivalents	6,734	(870)
Cash and cash equivalents, beginning of period	12,085	3,159
Cash and cash equivalents, end of period	$ 18,819	$ 2,289