Earnings per Common 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:
Net income (loss) attributable to common shareholders	$ 5,407	$ 1,753	$ (1,840)	$ (1,838)
Less: dividends paid on unvested share-based compensation	(83)	(127)	(166)	(254)
Undistributed earnings attributable to share-based compensation	0	0	0	0
Net income (loss) available to common shareholders	$ 5,324	$ 1,626	$ (2,006)	$ (2,092)
Denominator:
Weighted-average number of common shares-basic	52,908,195	50,193,672	51,959,049	45,026,715
Effect of dilutive share-based compensation	19,667	0	0	0
Weighted-average number of common shares-diluted	52,927,862	50,193,672	51,959,049	45,026,715
Net income (loss) per share attributable to common shareholders-basic	$ 0.10	$ 0.03	$ (0.04)	$ (0.05)
Net income (loss) per share attributable to common shareholders-diluted	$ 0.10	$ 0.03	$ (0.04)	$ (0.05)