Guarantees (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Guarantor Obligations [Line Items]
Derivative Liabilities	$ 10,300	$ 13,421
Notional amount of underlying interest rate swaps associated with risk participation agreements	3,277,127	$ 3,254,921
Financial Standby Letter Of Credit [Member]
Guarantor Obligations [Line Items]
Standby letters of credit, net liability	2,200
Contractual amount of letters of credit, guaranteed maximum potential future payments	325,600
Risk Participation Agreement [Member] | Indirect Guarantee Of Indebtedness [Member]
Guarantor Obligations [Line Items]
Derivative Liabilities	110
Notional amount of underlying interest rate swaps associated with risk participation agreements	$ 86,600
Minimum [Member] | Risk Participation Agreement [Member]
Guarantor Obligations [Line Items]
Term, in years	2 years
Maximum [Member] | Risk Participation Agreement [Member]
Guarantor Obligations [Line Items]
Term, in years	11 years