Commitments, Guarantees, and Contingent Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Letters of credit	$ 123,110	$ 103,684
Commitments to extend credit
Other Commitments [Line Items]
Commercial, industrial, and agricultural	2,296,304	1,852,040
Commercial real estate	334,528	296,053
Home equity	601,011	576,956
Other commitments	262,698	251,093
Total commitments to extend credit	$ 3,494,541	$ 2,976,142