Earnings per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:
Net income (loss) attributable to common shareholders	$ 23,737	$ 11,315	$ 38,325	$ 15,129
Less: dividends paid on unvested share-based compensation	(125)	(81)	(375)	(242)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	(63)	(11)	0	0
Net income (loss) available to common shareholders	$ 23,549	$ 11,223	$ 37,950	$ 14,887
Denominator:
Weighted-average number of common shares-basic	64,859,494	61,179,524	64,133,134	61,086,834
Effect of dilutive share-based compensation	486,694	168,339	480,315	192,418
Weighted-average number of common shares-diluted	65,346,188	61,347,863	64,613,449	61,279,252
Net income (loss) per share available to common shareholders-basic	$ 0.36	$ 0.18	$ 0.59	$ 0.24
Net income (loss) per share available to common shareholders-diluted	$ 0.36	$ 0.18	$ 0.59	$ 0.24