Note 22 - Commitments and Contingent Liabilities - Material Adverse Effect on Company's Financial Condition (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Standby Letters of Credit [Member]
Total Amounts Committed	$ 157,156
Less Than 1 Year	87,416
1-3 Years	69,740
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Employee Related Commitment [Member]
Total Amounts Committed	75,776
Less Than 1 Year	54,134
1-3 Years	21,642
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Environmental Commitment [Member]
Total Amounts Committed	398
Less Than 1 Year	0
1-3 Years	398
3-5 Years	0
Beyond 5 years	0
Standby Letters of Credit [Member] | Other Commitment [Member]
Total Amounts Committed	80,982
Less Than 1 Year	33,282
1-3 Years	47,700
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member]
Total Amounts Committed	651,608
Less Than 1 Year	647,058
1-3 Years	4,550
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Employee Related Commitment [Member]
Total Amounts Committed	83,524
Less Than 1 Year	83,524
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Environmental Commitment [Member]
Total Amounts Committed	563,705
Less Than 1 Year	559,155
1-3 Years	4,550
3-5 Years	0
Beyond 5 years	0
Surety Bond [Member] | Other Commitment [Member]
Total Amounts Committed	4,379
Less Than 1 Year	4,379
1-3 Years	0
3-5 Years	0
Beyond 5 years	0
Other Guarantee Obligations [Member] | Other Commitment [Member]
Total Amounts Committed	8,673
Less Than 1 Year	6,538
1-3 Years	1,554
3-5 Years	398
Beyond 5 years	$ 183