Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share
Net income attributable to common shares	$ 5,538	$ 3,883	$ 10,106	$ 6,616
Weighted-average common shares outstanding - basic	24,536,583	21,131,077	22,963,111	21,062,299
Effect of potentially dilutive common shares:
Stock options	363,760	371,536	373,438	368,516
Unvested awards	154,852	102,117	188,767	168,934
Weighted-average common shares outstanding - diluted	25,055,195	21,604,730	23,525,316	21,599,749
Net income per share attributable to common shares
Basic (in dollars per share)	$ 0.23	$ 0.18	$ 0.44	$ 0.31
Diluted (in dollars per share)	$ 0.22	$ 0.18	$ 0.43	$ 0.31
Weighted-average potentially dilutive securities excluded in calculation of basic and diluted income (loss) per share	43,013	165,552	141,081	202,422