Note 6 - Fair Value Measurements and Financial Instruments (Tables)
|6 Months Ended|
Jun. 30, 2019
|Fair Value, Assets Measured on Recurring Basis [Table Text Block]||
Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef