Other Assets and Other liabilities - Summary of Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other Assets And Other Liabilities [Abstract]
Cash surrender value on bank owned life insurance	$ 10,873	$ 10,556
Prepaid expenses	2,477	2,245
Software	1,962	2,296
Mortgage lending receivable	3,176	24
Derivatives	9,690	19,745
Other assets	16,038	16,488
Total other assets	$ 44,216	$ 51,354