Note 9 - Employee Retirement Plans - Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pension Plan [Member]
Service cost	$ 32	$ 32	$ 96	$ 96
Interest cost	28	22	82	65
Expected return on plan assets	(55)	(54)	(164)	(162)
Amortization of prior service cost (credit)	1	1	4	3
Recognition of actuarial loss (gain)			22	10
Total pension and postretirement benefit expense	6	1	40	12
Other Postretirement Benefits Plan [Member]
Service cost	3	3	7	8
Interest cost	3	3	11	11
Expected return on plan assets
Amortization of prior service cost (credit)	(2)	(1)	(4)	(4)
Recognition of actuarial loss (gain)	(2)		(3)	1
Total pension and postretirement benefit expense	$ 2	$ 5	$ 11	$ 16