Earnings Per Common 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
Basic Earnings Per Share:
Net income available to common shareholders		$ 11,109	$ 8,347	$ 22,846	$ 13,488
Less: Income allocated to participating securities		1	1	2	2
Net income allocated to common shareholders		$ 11,108	$ 8,346	$ 22,844	$ 13,486
Weighted average common shares outstanding including participating securities		20,399	20,304	20,370	19,596
Less: Participating securities		11	10	11	10
Average common shares	[1],[2]	20,388	20,294	20,359	19,586
Basic earnings per common share	[2]	$ 0.54	$ 0.41	$ 1.12	$ 0.69
Diluted Earnings Per Share:
Net income allocated to common shareholders		$ 11,108	$ 8,346	$ 22,844	$ 13,486
Weighted average common shares outstanding for basic earnings per common share		20,388	20,294	20,359	19,586
Add: Dilutive effects of stock options		104	114	107	110
Average shares and dilutive potential common shares		20,492	20,408	20,466	19,696
Diluted earnings per common share	[2]	$ 0.54	$ 0.41	$ 1.12	$ 0.68

[1] Share and per share data has been adjusted for a 2-for-1 stock split on July 12, 2018.

[2] Share and per share data has been adjusted to reflect a 2-for-1 stock split on July 12, 2018.