CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 120,579	$ 31,540
Accounts receivable, net	12,354	13,133
Prepaid expenses and other current assets	3,328	1,814
Total current assets	136,261	46,487
Property and equipment, net	13,426	9,224
Other noncurrent assets	397	1,513
Total assets	150,084	57,224
Current liabilities
Accounts payable	1,570	1,268
Accrued expenses and other current liabilities	10,636	9,661
Deferred revenue	3,757	618
Current portion of long-term debt	2,782	1,572
Total current liabilities	18,745	13,119
Long-term debt, less current portion	3,066	9,243
Other long-term liabilities	1,496	1,858
Total liabilities	23,307	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 June 30, 2013 and December 31, 2012, respectively		105,710
Stockholders' equity (deficit)
Common stock, $0.001 par value - 500,000 and 36,000 shares authorized, 32,724 and 4,942 shares issued, 32,472, and 4,658 outstanding at June 30, 2013 and December 31, 2012, respectively	32	5
Additional paid-in capital	223,692	4,638
Accumulated deficit	(96,947)	(77,349)
Total stockholders' equity (deficit)	126,777	(72,706)
Total liabilities, convertible preferred stock, and stockholders' equity (deficit)	$ 150,084	$ 57,224