Note 8 - Employee Retirement Plans - Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Plan [Member]
Service cost	$ 25	$ 32	$ 75	$ 96
Interest cost	45	28	133	82
Expected return on plan assets	(46)	(55)	(138)	(164)
Amortization of actuarial net gain
Amortization of prior service cost (credit)	2	1	5	4
Recognition of actuarial loss (gain)	12		(16)	22
Special termination benefit charge			5
Total pension and postretirement benefit expense (income)	38	6	64	40
Other Postretirement Benefits Plan [Member]
Service cost	1	3	4	7
Interest cost	6	3	17	11
Expected return on plan assets
Amortization of actuarial net gain	(6)		(17)
Amortization of prior service cost (credit)	(2)	(2)	(4)	(4)
Recognition of actuarial loss (gain)		(2)		(3)
Special termination benefit charge
Total pension and postretirement benefit expense (income)	$ (1)	$ 2	$ 0	$ 11