Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Net loss	$ (6,351)	$ (9,493)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,179	1,728
Employee stock-based compensation	4,542	4,176
Write-off of previously capitalized software costs		87
Impairment of assets held for sale and long-lived assets	56
Gain on disposal of property and equipment		(19)
Outside director restricted stock awarded in lieu of fees	50	50
Gain on sale of equity securities	(1,333)
Deferred tax benefit from unrealized gain on available-for-sale marketable securities	1,000	5,600
Deferred tax benefit from unrealized gain on available-for-sale marketable securities	(1,358)	(5,626)
Changes in assets and liabilities:
Accounts receivable	(1,665)	(63)
Prepaid expenses and other assets	(480)	(2,252)
Accounts payable	(2,441)	239
Accrued compensation and employee benefits	(2,181)	(1,320)
Accrued expenses and other liabilities	3,690	5,283
Deferred revenues	(57)	(67)
Net cash used in operating activities	(5,349)	(7,277)
Investing activities
Purchases of property and equipment	(5,311)	(4,369)
Purchases of marketable securities	(12,207)	(31,274)
Maturities of marketable securities	19,757	37,180
Proceeds from sales of marketable securities	3,579
Net cash provided by investing activities	5,818	1,537
Financing activities
Net proceeds from issuance of common stock under stock plans	632	2,379
Withholding taxes related to restricted stock units net share settlement	(2,929)	(3,427)
Net cash used in financing activities	(2,297)	(1,048)
Net decrease in cash and cash equivalents	(1,828)	(6,788)
Cash and cash equivalents at the beginning of the period	32,533	29,726
Cash and cash equivalents at the end of the period	30,705	22,938
Non-cash investing and financing activities
Accrued purchase of property and equipment	291	2,501
Change in fair value of equity investment	$ 3,787	$ 23,145