Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Statement of Cash Flows [Abstract]
Net (loss) income	$ (8,420)	$ 10,612
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, amortization and other	13,693	12,123
Stock-based compensation expense	3,479	4,028
Change in deferred tax assets and liabilities	(3,559)	3,363
Excess tax benefit from share-based compensation		(937)
Change in fair value of acquisition contingencies	42
Changes in assets and liabilities:
Accounts receivable	12,688	19,213
Inventories	4,114	(9,128)
Income taxes receivable	(1,154)	(2,266)
Prepaid expenses and other current and non-current assets	656	1,491
Accounts payable	(1,365)	(1,959)
Accrued payroll and related expenses	(813)	(985)
Income taxes payable	182	(3,803)
Other current and non-current liabilities	(2,251)	(2,436)
Net cash provided by operating activities	17,292	29,316
INVESTING ACTIVITIES:
Acquisitions of property and equipment	(6,619)	(11,748)
Acquisition of BioHelix, net of cash acquired	0	(9,150)
Acquisition of intangibles	(92)	(1,142)
Net cash used for investing activities	(6,711)	(22,040)
FINANCING ACTIVITIES:
Payments on lease obligation	(213)	(184)
Repurchases of common stock	(1,951)	(858)
Proceeds from issuance of common stock	2,376	4,922
Excess tax benefit from share-based compensation	0	937
Payment on line of credit	0	(5,000)
Payments on acquisition contingencies	(1,109)
Net cash used for financing activities	(897)	(183)
Effect of exchange rates on cash	3	0
Net increase in cash and cash equivalents	9,687	7,093
Cash and cash equivalents, beginning of period	8,388	14,856
Cash and cash equivalents, end of period	18,075	21,949
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	467	571
Cash paid for income taxes	443	1,900
NON-CASH INVESTING ACTIVITIES:
Purchase of capital equipment by incurring current liabilities	452	1,007
NON-CASH FINANCING ACTIVITIES:
Reduction of other current liabilities upon issuance of restricted share units	$ 663	$ 456