Condensed Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net income (loss)	$ (83,352)	$ 11,366	$ 19,984
Other comprehensive income:
Unrealized gain on available-for-sale securities, net of tax	22	34	3
Total comprehensive income (loss)	$ (83,330)	$ 11,400	$ 19,987