Note 8 - Leases (Details Textual) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Leveraged Leases, Net Investment in Leveraged Leases Disclosure, Residual Value of Leased Assets	$ 4	$ 4

The estimate of the value of the leased asset at the end of the lease term.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 30
-Paragraph 14
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureResidualValueOfLeasedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant