Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Numerator:
Net income (loss) attributable to common shareholders	$ 7,462	$ 2,825	$ 5,622	$ 987
Less: dividends paid on unvested share-based compensation	(83)	(127)	(249)	(381)
Undistributed earnings attributable to share-based compensation	0	0	0	0
Net income (loss) available to common shareholders	$ 7,379	$ 2,698	$ 5,373	$ 606
Denominator:
Weighted-average number of common shares-basic	58,714,055	50,771,355	54,227,155	46,962,639
Effect of dilutive share-based compensation	46,279	0	87,314	0
Weighted-average number of common shares-diluted	58,760,334	50,771,355	54,314,469	46,962,639
Net income (loss) per share attributable to common shareholders-basic	$ 0.13	$ 0.05	$ 0.10	$ 0.01
Net income (loss) per share attributable to common shareholders-diluted	$ 0.13	$ 0.05	$ 0.10	$ 0.01