Note 4 - Restricted Cash (Details Textual) $ in Millions	Jun. 30, 2018 USD ($)
Letter of Credit Issued for Workers Compensation Obligation [Member]
Letters of Credit Outstanding, Amount	$ 5.9

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

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