Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Computation of Earnings per share
Net (loss) income per consolidated statements of income	$ 2,596	$ (26,891)	$ 62	$ 3,796	$ 7,928	$ (8,864)	$ (1,796)	$ 2,962	$ (20,437)	$ 230	$ (37,273)
Net loss allocated to participating securities									(59)		(21)
Net (loss) earnings allocated to common stock									(20,378)	230	(37,252)
Basic earnings (loss) per common share computation:
Distributed earnings allocated to common stock
Undistributed (loss) earnings allocated to common stock									(20,378)	230	(37,252)
Net (loss) earnings allocated to common stock									(20,378)	230	(37,252)
Weighted average common shares outstanding, including shares considered participating securities									32,805	31,075	30,477
Less: Average participating securities									(94)	(49)	(20)
Weighted average shares									32,711	31,026	30,457
Basic (loss) earnings per common share									$ (0.62)	$ 0.01	$ (1.22)
Diluted earnings (loss) per common share computation:
Net (loss) earnings allocated to common stock									$ (20,378)	$ 230	$ (37,252)
Weighted average common shares outstanding for basic earnings per common share									32,711	31,026	30,457
Add: Dilutive effects of assumed exercises of stock options
Weighted average shares and dilutive potential common shares									32,711	31,026	30,457
Diluted (loss) earnings per common share									$ (0.62)	$ 0.01	$ (1.22)