Other Comprehensive (Loss) Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of securities, net	$ 0	$ (3)	$ 0	$ (9)
Tax expense	(237)	(3,221)	(271)	(2,632)
Interest expense	1,814	1,512	3,441	2,977
Net earnings	669	5,414	308	2,923
Unrealized gains and losses on securities available-for-sale: | Reclassifications Out of Accumulated Other Comprehensive (Loss) Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of securities, net	0	(3)	0	(9)
Tax expense	0	1	0	3
Net earnings	0	(2)	0	(6)
Gains on derivative instruments: | Interest Rate Contract | Reclassifications Out of Accumulated Other Comprehensive (Loss) Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax expense	13	0	21	0
Interest expense	(63)	0	(102)	0
Net earnings	$ (50)	$ 0	$ (81)	$ 0