Note 9 - Loans - Aging of Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Loans	$ 18,106,803	$ 16,342,479
Financial Asset, 30 to 59 Days Past Due [Member]
Loans	10,641	32,812
Financial Asset, 60 to 89 Days Past Due [Member]
Loans	8,948	13,015
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	3,172	1,439
Financial Asset, Past Due [Member]
Loans	90,886	113,112
Non-accrual loans	68,125	65,846
Financial Asset, Not Past Due [Member]
Loans	18,015,917	16,229,367
Commercial Portfolio Segment [Member]
Loans	3,367,437	2,982,399
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	7,223	4,294
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	3,151	9,877
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	1,112	1,439
Commercial Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans	38,090	32,168
Non-accrual loans	26,604	16,558
Commercial Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	3,329,347	2,950,231
Real Estate Construction Portfolio Segment [Member]
Loans	573,421	611,031
Real Estate Construction Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	0	0
Real Estate Construction Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	0	0
Real Estate Construction Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	0	0
Real Estate Construction Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans	0	0
Non-accrual loans	0	0
Real Estate Construction Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	573,421	611,031
Commercial Real Estate Portfolio Segment [Member]
Loans	8,677,733	8,143,272
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	0	8,389
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	1,107	0
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	2,060	0
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans	30,078	46,562
Non-accrual loans	26,911	38,173
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	8,647,655	8,096,710
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans	5,481,098	4,601,493
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	3,383	20,129
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	4,690	3,138
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	0	0
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans	22,674	34,382
Non-accrual loans	14,601	11,115
Residential Mortgage and Equity Lines Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans	5,458,424	4,567,111
Installment and Other Loans [Member ]
Loans	7,114	4,284
Installment and Other Loans [Member ] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans	35	0
Installment and Other Loans [Member ] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans	0	0
Installment and Other Loans [Member ] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans	0	0
Installment and Other Loans [Member ] | Financial Asset, Past Due [Member]
Loans	44	0
Non-accrual loans	9	0
Installment and Other Loans [Member ] | Financial Asset, Not Past Due [Member]
Loans	$ 7,070	$ 4,284