Note 8 - Employee Retirement Plans - Net Periodic Benefit Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Pension Plan [Member]
Service cost	$ 23	$ 32
Interest cost	45	27
Expected return on plan assets	(46)	(55)
Amortization of actuarial net gain
Amortization of prior service cost (credit)	2	1
Total pension and postretirement benefit expense	24	5
Other Postretirement Benefits Plan [Member]
Service cost	1	2
Interest cost	6	4
Expected return on plan assets
Amortization of actuarial net gain	(5)
Amortization of prior service cost (credit)	(1)	(1)
Total pension and postretirement benefit expense	$ 1	$ 5