Commitments, Guarantees, and Contingent Liabilities (Details) - Contractual or Notional Amounts of Financial Instruments - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Commitments to extend credit:
Letters of credit		$ 103,684	$ 112,728
Commitments to extend credit
Commitments to extend credit:
Commercial, industrial, and agricultural		1,852,040	1,729,286
Commercial real estate		296,053	296,882
Home equity		576,956	570,553
Other commitments	[1]	251,093	244,917
Total commitments to extend credit		$ 2,976,142	$ 2,841,638

[1] Other commitments includes installment and overdraft protection program commitments.