Note 6 - Retirement Plans (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Defined Contribution Plan, Expected Contributions, Remainder of Fiscal Year	$ 11
Profit Sharing Contribution [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	5	$ 7
Pension Plan [Member] | Gray Pension Plan [Member]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 4