Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities
Net loss	$ (23,402)	$ (13,535)
Adjustments to reconcile net loss to net cash used in operating activities
Loss (gain) on mark-to-market on convertible preferred stock warrants	(559)	716
Amortization of deferred lease benefits and tax incentives	(179)	(167)
Depreciation and amortization	1,380	1,316
Stock-based compensation	1,339	1,020
Changes in operating assets and liabilities
Accounts receivable	1,446	(4,873)
Prepaid expenses and other current assets	(763)	(1,324)
Accounts payable	(2,057)	(317)
Accrued expenses and other	(299)	219
Deferred revenues	3,362	5,782
Deferred lease benefits and tax incentive	329	1,212
Other assets and liabilities, net		7
Net cash used in operating activities	(19,403)	(9,944)
Cash flows from investing activities
Purchase of property and equipment	(326)	(563)
Other investing activities, net	(100)	2
Net cash used in investing activities	(426)	(561)
Cash flows from financing activities
Proceeds from issuance of common stock	148	48
Proceeds received in advance of Series G issuance		12,508
Deferred financing costs	(180)
Principal payment on capital lease obligations	(38)	(169)
Net cash provided by (used in) financing activities	(70)	12,387
Net increase (decrease) in cash and cash equivalents	(19,899)	1,882
Cash and cash equivalents, beginning of period	50,454	30,713
Cash and cash equivalents, end of period	30,555	32,595
Non cash investing and financing activities
Deferred financing costs included in ending accrued expenses	505
Supplemental disclosure of cash flows
Cash paid for interest		$ 6