Short-term Borrowings and Long-term FHLB Advances - Information Concerning Short-term Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Long-term Federal Home Loan Bank Advances [Abstract]
Balance at period-end	$ 252,367	$ 237,865
Maximum amount outstanding at any month end	302,932	237,865
Average balance outstanding during the period	$ 186,290	$ 128,008
Weighted-average interest rate, as of the period-end (as a percent)	2.23%	1.40%
Weighted-average interest rate, paid during the period (as a percent)	1.90%	1.09%