Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share
Shares not included in computation of diluted weighted average earnings per common	0	0	200,000	925
Net income attributable to common shareholders	$ 8,834	$ 4,939	$ 22,624	$ 18,436
Basic weighted average common shares outstanding (in shares)	5,900,000	6,055,000	5,960,000	6,068,000
Potentially dilutive common shares	104,000	129,000	123,000	147,000
Diluted weighted average common shares outstanding	6,004,000	6,184,000	6,083,000	6,215,000
Basic weighted average earnings per common share (in dollars per share)	$ 1.50	$ 0.82	$ 3.80	$ 3.04
Diluted earnings common share (in dollars per share)	$ 1.47	$ 0.80	$ 3.72	$ 2.97