Note 17 - Regulatory Matters (Details Textual) $ in Billions	6 Months Ended	12 Months Ended
Jun. 30, 2026	Dec. 31, 2025	Jan. 01, 2022 USD ($)
Capital Conservation Buffer	2.50%	2.50%
Required Assets To Liabilities Ratio After Dividend Effect	1.25
Minimum [Member]
Regulatory Assets, Total			$ 3

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478742/980-340-50-1

Name:	us-gaap_RegulatoryAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant