Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2017
OPERATING ACTIVITIES:
Net loss	$ (11,858)	$ (3,077)
Adjustments to reconcile net loss to net cash provided by (used for) operating activities:
Depreciation, amortization and other	17,597	17,813
Stock-based compensation expense	5,820	5,938
Amortization of debt discount and deferred issuance costs	4,266	4,129
Change in deferred tax assets and liabilities	(7,375)	101
Change in fair value of acquisition contingencies	(589)	0
Gain on extinguishment of Convertible Senior Notes	(421)	0
Changes in assets and liabilities:
Accounts receivable	(7,464)	(16,582)
Inventories	3,544	2,751
Income taxes receivable	(248)	(1,123)
Prepaid expenses and other current and non-current assets	(1,047)	(667)
Restricted cash	63	0
Accounts payable	984	2,128
Accrued payroll and related expenses	(1,867)	982
Income taxes payable	(12)	78
Deferred grant revenue	(3,658)	0
Other current and non-current liabilities	(2,541)	4,013
Net cash provided by (used for) operating activities:	(4,806)	16,484
INVESTING ACTIVITIES:
Acquisitions of property, equipment and intangibles	(7,860)	(12,767)
Acquisition of businesses, net of cash acquired	(5,061)	(14,388)
Net cash used for investing activities:	(12,921)	(27,155)
FINANCING ACTIVITIES:
Payments on lease obligation	(433)	(70)
Repurchases of common stock	(20,096)	(541)
Repurchases of Convertible Senior Notes	(4,459)	0
Proceeds from issuance of common stock	4,821	15,246
Payments on acquisition contingencies	(207)	(498)
Net cash provided by (used for) financing activities:	(20,374)	14,137
Effect of exchange rates on cash	(7)	20
Net increase (decrease) in cash and cash equivalents	(38,108)	3,486
Cash and cash equivalents, beginning of period		169,508
Cash and cash equivalents, end of period		172,994
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	3,331	3,279
Income taxes paid	459	1,259
NON-CASH INVESTING ACTIVITIES:
Purchase of property, equipment and intangibles by incurring current liabilities	1,866	653
NON-CASH FINANCING ACTIVITIES:
Reduction of other current liabilities upon issuance of restricted share units	$ 539	903
Senior 3 Point 25 Percent Convertible Notes Due 2020 [Member] | Convertible Debt [Member]
FINANCING ACTIVITIES:
Repurchases of Convertible Senior Notes		$ (4,500)