Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 39,814	$ 210,596
Due from Novartis Pharm, AG	960
Available for sale securities	423,746
Prepaid expenses and other current assets	8,812	6,804
Deferred tax assets	293
Total current assets	473,625	217,400
Property and equipment, net	1,555	27
Deferred tax assets, non-current	22,808
Security deposits	282	255
Other Assets	100
Total assets	498,370	217,682
Current liabilities
Accounts payable and accrued expenses	8,707	3,810
Accrued research and development expenses	7,918	2,485
Deferred revenue	3,206
Total current liabilities	19,831	6,295
Deferred revenue, long-term	206,418
Royalty purchase liability	125,000	41,667
Total liabilities	351,249	47,962
Stockholders' equity
Common stock-$0.001 par value, 200,000,000 shares authorized, 33,994,520 and 31,413,208 shares issued and outstanding at December 31, 2014 and 2013 respectively	34	31
Additional paid-in capital	428,390	352,739
Accumulated deficit	(281,238)	(183,050)
Accumulated other comprehensive income	(65)
Total stockholders' equity	147,121	169,720
Total liabilities and stockholders' equity	498,370	217,682
Preferred stock
Stockholders' equity
Preferred stock - $0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding