Note 6 - Warranty and Extended Service Contract (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Extended Product Warranty Accrual, Current	$ 2,232	$ 3,159

Amount at end of the reporting period of the aggregate extended product warranty liability that is expected to be paid within one year of the balance sheet date or normal operating cycle, if longer. Does not include the balance for the standard product warranty liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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