Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share
Shares not included in computation of diluted weighted average earnings per common	300,000	0	100,000	43,000
Net income attributable to common shareholders	$ 7,528	$ 5,657	$ 13,789	$ 13,495
Basic weighted average common shares outstanding	5,878,000	6,036,000	5,990,000	6,075,000
Potentially dilutive common shares	113,000	122,000	133,000	138,000
Diluted weighted average common shares outstanding	5,991,000	6,158,000	6,123,000	6,213,000
Basic earnings per common share: (in dollars per share)	$ 1.28	$ 0.94	$ 2.30	$ 2.22
Diluted earnings common share (in dollars per share)	$ 1.26	$ 0.92	$ 2.25	$ 2.17