Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 47,919	$ (4,898)	$ 34,254	$ (32,068)
Other comprehensive loss:
Change in unrealized gain on available-for-sale securities, net	0	(4)	0	(21)
Other comprehensive loss, net	0	(4)	0	(21)
Comprehensive income (loss)	$ 47,919	$ (4,902)	$ 34,254	$ (32,089)