Net (Loss) Income 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
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income	$ 16,938	$ 348	$ 48,282	$ 30,047
Less: Accretion of Series B preferred stock	(677)	(639)	(1,345)	(1,268)
Less: Net income allocated to unvested participating restricted stock	(388)	7	(1,169)	(846)
Net income (loss) available to common stockholders - basic	15,873	(284)	45,768	27,933
Effect of unvested participating restricted stock in two-class calculation	5	0	58	17
Net income available to common stockholders - diluted	15,878	(284)	47,171	27,950
Weighted average outstanding shares of common stock - basic	17,890,000	18,072,000	17,786,000	17,884,000
Dilutive Effect of Stock Options	248,000	0	282,000	396,000
Weighted average outstanding shares of common stock - diluted	18,138,000	18,072,000	18,731,000	18,280,000
Net income (loss) per common share - Basic	$ 0.89	$ (0.02)	$ 2.57	$ 1.56
Net income (loss) per common share - Diluted	$ 0.88	$ (0.02)	$ 2.52	$ 1.53
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	662,500	965,000		624,000
Series B Preferred Stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Less: Accretion of Series B preferred stock	(677)	(639)	(1,345)	(1,268)
Accretion of Series B Preferred Stock	$ 0	$ 0	$ 1,345	$ 0
Dilutive Effect of Series B Preferred Stock	0	0	663,000	0
Common Stock [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted average outstanding shares of common stock - diluted	18,138,000	18,072,000	18,731,000	18,280,000