Long-Term Borrowings and Subordinated Debt - Interest Expense and Weighted Average Interest Rates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Long-term borrowings	$ 70,314	$ 47,301	$ 14,713
Weighted average interest rate	2.84%	1.88%	2.91%
Interest expense	$ 1,129	$ 463	$ 670