Condensed Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income (loss)	$ (18,550)	$ (11,488)	$ (58,290)	$ 25,148
Other comprehensive income:
Unrealized gain on available-for-sale securities, net of tax	100	10	31	56
Total comprehensive income (loss)	$ (18,450)	$ (11,478)	$ (58,259)	$ 25,204