CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 113,672	$ 27,122
Accounts receivable, net	12,494	11,759
Other current assets	8,376	7,215
Total current assets	134,542	46,096
Property and equipment, net	23,198	21,975
Investment in unconsolidated joint venture	5,390	4,924
Goodwill, net	39,030	38,560
Intangible assets, net	23,052	24,444
Other assets	3,485	870
Total assets	228,697	136,869
Current liabilities:
Accounts payable	6,673	4,741
Accrued expenses	22,583	20,512
Deferred revenue	7,705	8,520
Total current liabilities	36,961	33,773
Convertible senior notes	81,670
Other noncurrent liabilities	5,271	5,086
Total liabilities	123,902	38,859
Commitments and contingencies (see note 17)
Stockholders' equity:
Series A convertible preferred stock
Common stock	39	39
Additional paid-in capital	2,138,529	2,132,189
Accumulated other comprehensive income	160	219
Accumulated deficit	(2,033,933)	(2,034,437)
Total stockholders' equity	104,795	98,010
Total liabilities and stockholders' equity	$ 228,697	$ 136,869