Note 13 - Commitments and Contingent Liabilities - Material Adverse Effect on Company's Financial Condition (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Standby Letters of Credit [Member]
Total Amounts Committed	$ 193,307
Less Than 1 Year	193,307
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Employee Related Commitment [Member]
Total Amounts Committed	58,835
Less Than 1 Year	58,835
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Environmental Commitment [Member]
Total Amounts Committed	398
Less Than 1 Year	398
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Other Commitment [Member]
Total Amounts Committed	134,074
Less Than 1 Year	134,074
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member]
Total Amounts Committed	621,142
Less Than 1 Year	568,807
1-3 Years	52,335
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Employee Related Commitment [Member]
Total Amounts Committed	81,524
Less Than 1 Year	63,989
1-3 Years	17,535
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Environmental Commitment [Member]
Total Amounts Committed	535,303
Less Than 1 Year	501,335
1-3 Years	33,968
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Other Commitment [Member]
Total Amounts Committed	4,315
Less Than 1 Year	3,483
1-3 Years	832
3-5 Years	0
Beyond 5 years	$ 0