Note 8 - Employee Retirement Plans - Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pension Plan [Member]
Service cost	$ 23	$ 23
Interest cost	46	45
Expected return on plan assets	(48)	(46)
Amortization of prior service cost (credit)	1	2
Total pension and postretirement benefit expense (income)	22	24
Other Postretirement Benefits Plan [Member]
Service cost	1	1
Interest cost	5	6
Amortization of actuarial net gain	(5)	(5)
Amortization of prior service cost (credit)	(2)	(1)
Total pension and postretirement benefit expense (income)	$ (1)	$ 1