Note 8 - Employee Retirement Plans - Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Plan [Member]
Service cost	$ 32	$ 32	$ 64	$ 64
Interest cost	27	21	54	43
Expected return on plan assets	(54)	(54)	(109)	(108)
Amortization of prior service cost (credit)	2	1	3	2
Recognition of actuarial loss (gain)	22	10	22	10
Total pension and postretirement benefit expense	29	10	34	11
Other Postretirement Benefits Plan [Member]
Service cost	2	3	4	5
Interest cost	4	4	8	8
Expected return on plan assets
Amortization of prior service cost (credit)	(1)	(2)	(2)	(3)
Recognition of actuarial loss (gain)	(1)	1	(1)	1
Total pension and postretirement benefit expense	$ 4	$ 6	$ 9	$ 11