Note 13 - Recent Accounting and Reporting Developments (Details Textual) - Reclassification from Cost of Sales to Other Income (Expense) [Member] $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Three Months Ended June 30, 2017 [Member]
Prior Period Reclassification Adjustment	$ 0.1
Six Months Ended June 30, 2017 [Member]
Prior Period Reclassification Adjustment	$ 0.2

The amount of a reclassification adjustment made to prior period financial statement amounts.

No definition available.

Name:	us-gaap_PriorPeriodReclassificationAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration