Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Comprehensive Loss
Net income (loss)	$ 31,060	$ 38,611	$ 12,464	$ (5,078)	$ (22,628)	$ (50,744)	$ (12,858)	$ 29,311	$ 93,499	$ (91,308)	$ (27,066)
Unrealized loss on marketable securities									(4,975)
Other comprehensive loss									(4,975)	(5)
COMPREHENSIVE INCOME (LOSS)									$ 88,524	$ (91,313)	$ (27,066)