Note 11 - Employee Retirement Plans - Summary of Net Periodic Benefit Cost (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plan [Member]
Service cost	$ 22,000,000	$ 22,000,000	$ 65,000,000	$ 67,000,000
Interest cost	31,000,000	36,000,000	93,000,000	109,000,000
Expected return on plan assets	(41,000,000)	(44,000,000)	(124,000,000)	(133,000,000)
Amortization of net loss	0	0	0	0
Amortization of prior service cost (credit)	1,000,000	2,000,000	4,000,000	5,000,000
Recognition of actuarial loss	26,000,000	0	60,000,000	8,000,000
Total pension and postretirement benefit expense	39,000,000	16,000,000	98,000,000	56,000,000
Other Postretirement Benefit Plan [Member]
Service cost	3,000,000	3,000,000	7,000,000	10,000,000
Interest cost	6,000,000	8,000,000	19,000,000	24,000,000
Expected return on plan assets	0	0	0	0
Amortization of net loss	0	1,000,000	(1,000,000)	3,000,000
Amortization of prior service cost (credit)	(1,000,000)	(2,000,000)	(3,000,000)	(5,000,000)
Recognition of actuarial loss	0	0	0	0
Total pension and postretirement benefit expense	$ 8,000,000	$ 10,000,000	$ 22,000,000	$ 32,000,000