Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 51,778	$ 42,707	$ 46,514
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,474	17,485	14,126
Share-based Compensation	8,558	6,775	6,082
Deferred taxes	1,174	2,780	2,837
Loss on impairment of assets	513	455
Gain on acquisition			(344)
Amortization of held-to-maturity securities	1,063	1,173	1,234
Other	(153)	(1,541)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(9,933)	900	(11,371)
Inventories	(985)	136	(2,097)
Prepaid expenses and other	(691)	(1,312)	(2,047)
Income taxes	1,646	8,207	(2,310)
Accounts payable	3,176	(1,116)	5,781
Accrued liabilities and other	7,128	850	5,691
Net cash provided by operating activities	81,748	77,499	64,096
Investing activities
Purchases of property and equipment	(32,635)	(33,616)	(44,362)
Cash used for acquisitions, net of cash acquired	(110,533)		(5,032)
Purchases of other assets and investments	(8,742)
Purchases of marketable securities	(20,037)	(89,315)	(66,393)
Proceeds from maturities of marketable securities	47,972	62,176	52,193
Net cash used in investing activities	(123,975)	(60,755)	(63,594)
Financing activities
Payments on debt			(152)
Proceeds from issuance of debt	5,000
Acquisition-related contingent consideration		(400)	(1,400)
Repurchases of common stock	(4,410)
Proceeds from exercises of stock options and other	8,602	5,715	6,251
Net cash provided by financing activities	9,192	5,315	4,699
Effect of exchange rate changes on cash and cash equivalents	947	(917)	(877)
Net (decrease) increase in cash and cash equivalents	(32,088)	21,142	4,324
Cash and cash equivalents, beginning of period	68,795	47,653	43,329
Cash and cash equivalents, end of period	36,707	68,795	47,653
Supplemental cash flow disclosure
Cash paid for interest	19	1	5
Cash paid for taxes	$ 19,113	$ 9,802	$ 20,330

The sum of the periodic adjustments of the differences between securities' face values and purchase prices that are charged against earnings. This is called accretion if the security was purchased at a discount and amortization if it was purchased at premium. As a noncash item, this element is an adjustment to net income when calculating cash provided by or used in operations using the indirect method.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.