Note 7 - Inventories - Fair Value of Impaired Inventory (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)
Impairment Data; Total Subdivisions Tested	16	24
Impairment Data; Inventory Impairments	$ 610	$ 550
Impairment Data; Fair Value of Inventory After Impairments	$ 10,476	$ 5,223
Impairment Data; Number of Subdivisions Impaired	2	2
Measurement Input, Discount Rate [Member] \| Minimum [Member]
Quantitative Data; Discount Rate		0.12

Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116847112&loc=d3e4542-108314

Name:	us-gaap_InventoryWriteDown
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration