Note 17 - Commitments and Contingencies (Tables)
|12 Months Ended|
Dec. 31, 2018
|Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]||
Tabular disclosure of unconditional purchase obligations that are not recognized as a liability on the balance sheet, including the nature and significant terms of an unconditional purchase obligation; the amount of the fixed and determinable portion of the obligation as of the date of the latest balance sheet presented in the aggregate and, if determinable, for each of the five succeeding fiscal years; the nature of any variable components of the obligation; the amount purchased under the obligation (for example, the take-or-pay or throughput contract) for the reporting period; and may include the amount of imputed interest necessary to reduce the obligation to present value.
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef