Note 23 - Regulatory Matters - Capital and Leverage Ratios (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Common Equity Tier 1 to Risk-Weighted Assets, Actual amount	$ 2,501,439,000	$ 2,276,830,000
Common Equity Tier 1 to Risk-Weighted Assets, Actual ratio	13.23%	12.75%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required	$ 1,323,846,000	$ 1,250,461,000
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required, Ratio	7.00%	7.00%
Common Equity Tier 1 to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,229,286,000	$ 1,161,142,000
Common Equity Tier 1 to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual amount	$ 2,501,439,000	$ 2,276,830,000
Tier 1 Capital to Risk-Weighted Assets, Actual ratio	0.1323	0.1275
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required	$ 1,607,527,000	$ 1,518,417,000
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,512,967,000	$ 1,429,098,000
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	0.08	0.08
Total Capital to Risk-Weighted Assets, Actual amount	$ 2,665,054,000	$ 2,432,045,000
Total Capital to Risk-Weighted Assets, Actual ratio	0.1409	0.1361
Total Capital to Risk-Weighted Assets, Minimum Capital Required	$ 1,985,769,000	$ 1,875,691,000
Total Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,891,209,000	$ 1,786,373,000
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	0.10	0.10
Leverage Ratio, Actual amount	$ 2,501,439,000	$ 2,276,830,000
Leverage Ratio, Actual ratio	0.1087	0.1053
Leverage Ratio, Minimum Capital Required	$ 920,670,000	$ 864,918,000
Leverage Ratio Minimum Capital Required, Ratio	0.04	0.04
Leverage Ratio, Required to be Considered Well Capitalized	$ 1,150,838,000	$ 1,081,148,000
Leverage Ratio Required to be Considered Well Capitalized, Ratio	0.05	0.05
Bank [Member]
Common Equity Tier 1 to Risk-Weighted Assets, Actual amount	$ 2,430,773,000	$ 2,182,066,000
Common Equity Tier 1 to Risk-Weighted Assets, Actual ratio	12.84%	12.21%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required	$ 1,325,277	$ 1,250,914
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required, Ratio	7.00%	7.00%
Common Equity Tier 1 to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,230,615,000	$ 1,161,563,000
Common Equity Tier 1 to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual amount	$ 2,430,773,000	$ 2,182,066,000
Tier 1 Capital to Risk-Weighted Assets, Actual ratio	0.1284	0.1221
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required	$ 1,609,265,000	$ 1,518,967,000
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,514,602,000	$ 1,429,616,000
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	0.08	0.08
Total Capital to Risk-Weighted Assets, Actual amount	$ 2,709,888,000	$ 2,452,781,000
Total Capital to Risk-Weighted Assets, Actual ratio	0.1431	0.1373
Total Capital to Risk-Weighted Assets, Minimum Capital Required	$ 1,987,916,000	$ 1,876,371,000
Total Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized	$ 1,893,253,000	$ 1,787,020,000
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	0.10	0.10
Leverage Ratio, Actual amount	$ 2,430,773,000	$ 2,182,066,000
Leverage Ratio, Actual ratio	0.1055	0.1008
Leverage Ratio, Minimum Capital Required	$ 921,473,000	$ 865,470,000
Leverage Ratio Minimum Capital Required, Ratio	0.04	0.04
Leverage Ratio, Required to be Considered Well Capitalized	$ 1,151,841,000	$ 1,081,838,000
Leverage Ratio Required to be Considered Well Capitalized, Ratio	0.05	0.05