Borrowings - Summary of Information Pertaining to Borrowings (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 580,200	$ 590,161
Long-term borrowings, Balance	91,053	92,920
Total Borrowings, Balance	$ 671,253	$ 683,081
Short-term borrowings, Weighted Average Rate	2.22%	1.38%
Long-term borrowings, Weighted Average Rate	3.59%	2.81%
Total Borrowings, Weighted Average Rate	2.41%	1.57%
Securities sold under repurchase agreements
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 45,200	$ 50,161
Short-term borrowings, Weighted Average Rate	0.50%	0.39%
Short-term borrowings
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 535,000	$ 540,000
Short-term borrowings, Weighted Average Rate	2.37%	1.47%
Long-term borrowings
Long Term And Short Term Debt [Line Items]
Long-term borrowings, Balance	$ 45,434	$ 47,301
Long-term borrowings, Weighted Average Rate	2.39%	1.88%
Junior subordinated debt securities
Long Term And Short Term Debt [Line Items]
Long-term borrowings, Balance	$ 45,619	$ 45,619
Long-term borrowings, Weighted Average Rate	4.79%	3.78%