Note 6 - Commitments and Contingencies (Tables)
|6 Months Ended|
Jun. 30, 2017
|Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]||
Tabular disclosure of future minimum payments required in the aggregate and for each of the five succeeding fiscal years for operating leases having initial or remaining noncancelable lease terms in excess of one year and the total minimum rentals to be received in the future under noncancelable subleases as of the balance sheet date.
Reference 1: http://www.xbrl.org/2003/role/presentationRef