Note 6 - Earnings Per Share (Tables)
|12 Months Ended|
Dec. 31, 2017
|Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]||
Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations.
Reference 1: http://www.xbrl.org/2003/role/presentationRef