Note 6 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Property, Plant, and Equipment, Lessor Asset under Operating Lease, before Accumulated Depreciation	$ 305.4
Property, Plant, and Equipment, Lessor Asset under Operating Lease, Accumulated Depreciation	199.3
Depreciation, Total	$ 9.4	$ 11.0

Amount of accumulated depreciation of lessor's underlying asset for which right to use has been conveyed to lessee under operating lease.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123405975&loc=d3e41551-112718

Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123422147&loc=d3e41460-112716

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919398-209981

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