Borrowings - Summary of Information Pertaining to Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 569,617	$ 590,161
Long-term borrowings, Balance	92,303	92,920
Total Borrowings, Balance	$ 661,920	$ 683,081
Short-term borrowings, Weighted Average Rate	1.75%	1.38%
Long-term borrowings, Weighted Average Rate	3.32%	2.81%
Total Borrowings, Weighted Average Rate	1.97%	1.57%
Securities sold under repurchase agreements
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 44,617	$ 50,161
Short-term borrowings, Weighted Average Rate	0.42%	0.39%
Short-term borrowings
Long Term And Short Term Debt [Line Items]
Short-term borrowings, Balance	$ 525,000	$ 540,000
Short-term borrowings, Weighted Average Rate	1.86%	1.47%
Long-term borrowings
Long Term And Short Term Debt [Line Items]
Long-term borrowings, Balance	$ 46,684	$ 47,301
Long-term borrowings, Weighted Average Rate	2.09%	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	4.58%	3.78%