Note 7 - Loans and the Allowance for Credit Losses - Loans Purchased with Credit Deterioration (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Total purchased credit-deteriorated loans	$ 11,435,643	$ 11,457,558
Financial Asset Acquired with Credit Deterioration [Member]
Total purchased credit-deteriorated loans	71,000	221,130
Commercial Portfolio Segment [Member]
Total purchased credit-deteriorated loans	1,656,916	1,565,963
Commercial Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Total purchased credit-deteriorated loans	4,670	5,398
Commercial Real Estate Portfolio Segment [Member]
Total purchased credit-deteriorated loans	7,981,622	8,054,696
Commercial Real Estate Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Total purchased credit-deteriorated loans	64,447	213,770
Residential Portfolio Segment [Member]
Total purchased credit-deteriorated loans	1,207,092	1,210,980
Residential Portfolio Segment [Member] \| Financial Asset Acquired with Credit Deterioration [Member]
Total purchased credit-deteriorated loans	$ 1,883	$ 1,962