Note 6 - Schedule of Other Long-Term Assets (Details) (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other Assets Noncurrent Disclosure [Abstract]
Reserve for long-term receivables	$ 0	$ 4

Amount of allowance for credit loss on accounts receivable, classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivableNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant