Note 14 - Commitments and Contingent Liabilities - Material Adverse Effect on Company's Financial Condition (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Standby Letters of Credit [Member]
Total Amounts Committed	$ 183,990
Less Than 1 Year	142,568
1-3 Years	41,422
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Employee Related Commitment [Member]
Total Amounts Committed	58,768
Less Than 1 Year	37,074
1-3 Years	21,694
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	124,824
Less Than 1 Year	105,096
1-3 Years	19,728
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member]
Total Amounts Committed	625,692
Less Than 1 Year	568,702
1-3 Years	56,990
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Employee Related Commitment [Member]
Total Amounts Committed	83,524
Less Than 1 Year	48,024
1-3 Years	35,500
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Environmental Commitment [Member]
Total Amounts Committed	537,822
Less Than 1 Year	516,537
1-3 Years	21,285
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Other Commitment [Member]
Total Amounts Committed	4,346
Less Than 1 Year	4,141
1-3 Years	205
3-5 Years	0
Beyond 5 years	0
Other Guarantee Obligations [Member] | Other Commitment [Member]
Total Amounts Committed	6,889
Less Than 1 Year	6,889
1-3 Years	0
3-5 Years	0
Beyond 5 years	$ 0