CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 115,490	$ 31,540
Accounts receivable, net	12,116	13,133
Prepaid expenses and other current assets	2,940	1,814
Total current assets	130,546	46,487
Property and equipment, net	11,326	9,224
Other noncurrent assets	397	1,513
Total assets	142,269	57,224
Current liabilities
Accounts payable	2,473	1,268
Accrued expenses and other current liabilities	11,015	9,661
Deferred revenue	1,382	618
Current portion of long-term debt	2,551	1,572
Total current liabilities	17,421	13,119
Long-term debt, less current portion	3,454	9,243
Other long-term liabilities	1,670	1,858
Total liabilities	22,545	24,220
Convertible preferred stock, net of issuance costs $0.001 par value - 10,000 and 18,804 shares authorized, 0 and 18,753 shares issued and outstanding at March 31, 2013 and December 31, 2012, respectively		105,710
Stockholders' equity (deficit)
Common stock, $0.001 par value - 500,000 and 36,000 shares authorized, 31,427 and 4,942 shares issued, 31,125, and 4,658 outstanding at March 31, 2013 and December 31, 2012, respectively	31	5
Additional paid-in capital	207,543	4,638
Accumulated deficit	(87,850)	(77,349)
Total stockholders' equity (deficit)	119,724	(72,706)
Total liabilities, convertible preferred stock, and stockholders' equity (deficit)	$ 142,269	$ 57,224