Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 66,897	$ 65,086
Available-for-sale securities	57,279	90,116
Restricted cash	101	101
Accounts receivable	12,155	5,857
Prepaid expenses and other current assets	2,450	5,484
Total current assets	138,882	166,644
Restricted cash	584	584
Property and equipment, net	13,779	13,364
Other assets	167	175
Intangible assets, net	1,765	1,845
In-process research and development	6,200	6,200
Goodwill	3,605	3,605
Total assets	164,982	192,417
Current liabilities:
Accounts payable, accrued expenses and other	34,110	38,814
Deferred revenues	9,527	9,336
Deferred rent	1,330	1,336
Long-term debt, current portion	12,022	8,248
Total current liabilities	56,989	57,734
Deferred revenues, net of current portion	64,110	66,139
Deferred rent, net of current portion	6,266	6,538
Deferred tax incentives, net of current portion	424	507
Long-term debt, net of current portion	101,789	103,427
Accrued interest	1,200	1,200
Total liabilities	230,778	235,545
Commitments and contingencies (Note 10)
Non-controlling interest	168	337
Stockholders' deficit:
Preferred stock, $0.01 par value: 10,000 shares authorized at March 31, 2014 and December 31, 2013; no shares issued or outstanding at March 31, 2014 or December 31, 2013
Common stock, $0.01 par value: 200,000 shares authorized at March 31, 2014 and December 31, 2013; 103,361 and 102,523 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	1,034	1,025
Additional paid-in capital	532,840	527,779
Accumulated other comprehensive loss	(8)	(24)
Accumulated deficit	(599,830)	(572,245)
Total stockholders' deficit	(65,964)	(43,465)
Total liabilities, non-controlling interest and stockholders' deficit	$ 164,982	$ 192,417