Note 7 - Retirement Plans (Details Textual) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Defined Contribution Plan, Expected Contributions, Remainder of Fiscal Year	$ 5
Profit Sharing Contribution [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	20	$ 9
Pension Plan [Member] | Gray Pension Plan [Member]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 4