Note 13 - Retirement Plans and Other Postretirement Benefits (Details Textual) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Mar. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Increase in discount rates	$ 22
Remeasurement discount rate	5.26%	5.26%	5.45%
Remeasurement of teasury rate	4.59%	4.59%	4.75%
Actuarial gain (Loss)		$ (68)
Expected rate of return on plan assets assumption			5.20%
KRIP's Projected Benefit Obligation ("PBO") [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (Loss)	$ (90)
Remeasurement, as Actual Asset Returns Higher than Expected Returns [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (Loss)		$ 22