Earnings Per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic Net Income per Common Share Available to Common Stockholders [Abstract]
Net income					$ 6,797,000	$ 5,308,000	$ 4,929,000	$ 4,806,000	$ 26,684,000	$ 21,840,000	$ 16,512,000
Preferred stock dividends									0	(825,000)	(2,200,000)
Net income available to common stockholders	$ 4,625,000	$ 7,595,000	$ 8,200,000	$ 6,264,000	$ 6,797,000	$ 5,308,000	$ 4,654,000	$ 4,256,000	$ 26,684,000	$ 21,015,000	$ 14,312,000
Weighted average common shares outstanding									12,531,659	10,149,099	7,775,490
Basic earnings per common share	$ 0.37	$ 0.61	$ 0.66	$ 0.50	$ 0.55	$ 0.51	$ 0.51	$ 0.50	$ 2.13	$ 2.07	$ 1.84
Diluted Net Income per Common Share Available to Common Stockholders [Abstract]
Net income available to common stockholders	$ 4,625,000	$ 7,595,000	$ 8,200,000	$ 6,264,000	$ 6,797,000	$ 5,308,000	$ 4,654,000	$ 4,256,000	$ 26,684,000	$ 21,015,000	$ 14,312,000
Effect of assumed preferred stock conversion									0	825,000	2,200,000
Net income applicable to diluted earnings per share									$ 26,684,000	$ 21,840,000	$ 16,512,000
Weighted average common shares outstanding									12,531,659	10,149,099	7,775,490
Dilutive potential common shares [Abstract]
Assumed conversion of stock options									4,875	3,111	0
Restricted stock awarded									0	4,107	6,851
Assumed conversion of preferred stock									0	507,393	1,355,348
Dilutive potential common shares									4,875	514,611	1,362,199
Diluted weighted average common shares outstanding									12,536,534	10,663,710	9,137,689
Diluted earnings per common share	$ 0.37	$ 0.61	$ 0.66	$ 0.50	$ 0.55	$ 0.51	$ 0.50	$ 0.49	$ 2.13	$ 2.05	$ 1.81
Stock options to purchase shares of common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share (in shares)									0	0	45,500