Note 11 - Employee Retirement Plans - Summary of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Pension Plan [Member]
Service cost	$ 21	$ 22	$ 43	$ 45
Interest cost	31	37	62	73
Expected return on plan assets	(41)	(44)	(83)	(89)
Amortization of net loss
Amortization of prior service cost (credit)	2	1	3	3
Recognition of actuarial loss	28	8	35	8
Total pension and postretirement benefit expense	41	24	60	40
Other Postretirement Benefit Plan [Member]
Service cost	2	4	4	7
Interest cost	6	8	13	16
Expected return on plan assets
Amortization of net loss		1		2
Amortization of prior service cost (credit)	(1)	(2)	(2)	(3)
Recognition of actuarial loss
Total pension and postretirement benefit expense	$ 7	$ 11	$ 15	$ 22