Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share
Net income attributable to common shares	$ 9,342	$ 6,920	$ 5,538	$ 4,568	$ 4,664	$ 3,147	$ 3,883	$ 2,733	$ 26,368	$ 14,427	$ 10,503
Weighted-average common shares outstanding - basic									25,218,500	21,161,614	20,826,622
Effect of potentially dilutive common shares:
Stock options									302,264	349,533	383,743
Unvested awards									185,804	229,560	292,847
Weighted-average common shares outstanding - diluted									25,706,568	21,740,707	21,503,212
Net income per share attributable to common shares
Basic (in dollars per share)	$ 0.32	$ 0.26	$ 0.23	$ 0.21	$ 0.22	$ 0.15	$ 0.18	$ 0.13	$ 1.05	$ 0.68	$ 0.50
Diluted (in dollars per share)	$ 0.32	$ 0.26	$ 0.22	$ 0.21	$ 0.21	$ 0.14	$ 0.18	$ 0.13	$ 1.03	$ 0.66	$ 0.49
Weighted-average potentially dilutive securities excluded in calculation of basic and diluted income (loss) per share									117,048	180,020	169,875