Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator:
Net income (loss) attributable to common shareholders	$ 16,591	$ 8,730	$ 14,588	$ 3,814
Less: dividends paid on unvested share-based compensation	(125)	(81)	(250)	(161)
Undistributed earnings attributable to share-based compensation	(14)	0	0	0
Net income (loss) available to common shareholders	$ 16,452	$ 8,649	$ 14,338	$ 3,653
Denominator:
Weighted-average number of common shares-basic	63,764,929	61,082,770	63,763,935	61,039,721
Effect of dilutive share-based compensation	360,128	113,626	386,331	155,313
Weighted-average number of common shares-diluted	64,125,057	61,196,396	64,150,266	61,195,034
Net income (loss) per share available to common shareholders-basic	$ 0.26	$ 0.14	$ 0.22	$ 0.06
Net income (loss) per share available to common shareholders-diluted	$ 0.26	$ 0.14	$ 0.22	$ 0.06