Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities
Net income (loss)	$ (15,533)	$ (19,110)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	8,593	10,724
Deferred income taxes	465	607
Share-based compensation expense	4,388	3,998
Asset impairment		126
Provision for bad debts	160
Changes in operating assets and liabilities:
Accounts receivable	(6,958)	(4,200)
Inventories and deferred cost of sales	1,274	(7,249)
Prepaid expenses and other current assets	(6,660)	(8,970)
Accounts payable and accrued expenses	(2,210)	11,157
Customer deposits and deferred revenue	(1,510)	13,989
Income taxes receivable and payable, net	(893)	2,600
Other, net	86	616
Net cash provided by (used in) operating activities	(18,798)	4,288
Cash Flows from Investing Activities
Capital expenditures	(3,988)	(4,781)
Proceeds from the liquidation of investments	10,930	43,556
Payments for purchases of investments		(11,998)
Proceeds from sale of lab tools		1,413
Other	(213)	(68)
Net cash provided by investing activities	6,729	28,122
Cash Flows from Financing Activities
Proceeds (tax withholdings) from stock option exercises	(22)	45
Restricted stock tax withholdings	(27)	(52)
Purchases of common stock	(13,349)
Repayments of long-term debt	(82)	(76)
Net cash used in financing activities	(13,480)	(83)
Effect of exchange rate changes on cash and cash equivalents	39	(15)
Net increase (decrease) in cash and cash equivalents	(25,510)	32,312
Cash and cash equivalents - beginning of period	269,232	270,811
Cash and cash equivalents - end of period	243,722	303,123
Supplemental Disclosure of Cash Flow Information
Interest paid	39	36
Income taxes paid	$ 966	$ 544