Commitments, Guarantees, and Contingent Liabilities (Details) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Other Commitments [Line Items]
Letters of credit		$ 114,304	$ 112,728
Commitments to extend credit
Other Commitments [Line Items]
Commercial, industrial, and agricultural		1,699,246	1,729,286
Commercial real estate		283,183	296,882
Home equity		583,198	570,553
Other commitments	[1]	256,356	244,917
Total commitments to extend credit		$ 2,821,983	$ 2,841,638

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