Commitments and Credit Risk (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Outstanding letters of credit	$ 49,029,000	$ 71,074,000
Federal Home Loan Bank Certificates and Obligations (FHLB)
Other Commitments [Line Items]
Outstanding letters of credit	$ 1,549,214,000	$ 1,496,367,000
Term of debt instrument	1 year	1 year
Standby Letters of Credit
Other Commitments [Line Items]
Deferred revenue	$ 0	$ 0
Minimum
Other Commitments [Line Items]
Term of letter of credit	9 months	9 months
Maximum
Other Commitments [Line Items]
Term of letter of credit	15 years	15 years
Credit Card Commitments
Other Commitments [Line Items]
Outstanding commitments to extend credit	$ 671,488,000	$ 634,788,000
Other Loan Commitments
Other Commitments [Line Items]
Outstanding commitments to extend credit	2,355,953,000	3,991,931,000
Fixed Rate Residential Mortgage
Other Commitments [Line Items]
Outstanding commitments to extend credit	$ 213,998,000	$ 51,136,000