Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES:
Net (loss) income	$ 2,448	$ (11,286)
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Depreciation, amortization and other	11,577	12,410
Stock-based compensation expense	4,059	4,086
Amortization of debt discount and deferred issuance costs	2,741	2,854
Change in deferred tax assets and liabilities	(247)	(7,218)
Gain on extinguishment of Convertible Senior Notes		(421)
Changes in assets and liabilities:
Accounts receivable	5,156	2,494
Inventories	3,216	3,818
Income taxes receivable	(866)	63
Prepaid expenses and other current and non-current assets	(1,908)	(915)
Restricted cash	0	63
Accounts payable	(4,064)	(1,942)
Accrued payroll and related expenses	637	(1,526)
Income taxes payable	38	(2)
Deferred grant revenue	0	(2,697)
Other current and non-current liabilities	1,220	(2,237)
Net cash provided by (used for) operating activities:	24,007	(2,456)
INVESTING ACTIVITIES:
Acquisitions of property, equipment and intangibles	(8,070)	(5,424)
Acquisition of businesses, net of cash acquired	(14,655)	(5,094)
Net cash used for investing activities:	(22,725)	(10,518)
FINANCING ACTIVITIES:
Payments on lease obligation	(44)	(285)
Repurchases of common stock	(488)	(20,079)
Repurchases of Convertible Senior Notes	0	(4,459)
Proceeds from issuance of common stock	5,265	2,098
Payments on acquisition contingencies	(486)	(195)
Net cash provided by (used for) financing activities:	4,247	(22,920)
Effect of exchange rates on cash	11	(10)
Net increase (decrease) in cash and cash equivalents	5,540	(35,904)
Cash and cash equivalents, beginning of period	169,508
Cash and cash equivalents, end of period	175,048
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	3,140	3,243
Income tax paid	1,182	409
NON-CASH INVESTING ACTIVITIES:
Purchase of property, equipment and intangibles by incurring current liabilities	2,404	953
NON-CASH FINANCING ACTIVITIES:
Reduction of other current liabilities upon issuance of restricted share units	903	$ 539
Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member] | Convertible Debt [Member]
FINANCING ACTIVITIES:
Repurchases of Convertible Senior Notes	$ (4,500)