Note 7 - Leases - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 52	$ 50
Operating cash flows from finance leases	2	1
Financing cash flows from finance leases	4	3
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	57	24
Finance leases	$ 32	$ 13