Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator (both basic and diluted):
Net income (loss)	$ 14,737	$ 16,550	$ 34,368	$ (1,943)
Denominator:
Denominator for basic earnings per share	41,153,722	40,356,049	40,958,196	40,135,143
Stock options	167,272	422,110	195,703
Unvested restricted stock	105,092	557,505	565,695
Denominator for diluted earnings per share	41,426,086	41,335,664	41,719,594	40,135,143
Basic earnings per common share:	$ 0.36	$ 0.41	$ 0.84	$ (0.05)
Diluted earnings per common share:	$ 0.36	$ 0.40	$ 0.82	$ (0.05)