Note 5 - Marketable Securities (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Trading Securities, Realized Gain (Loss), Total	$ 72,950	$ 34,884
Trading Securities, Change in Unrealized Holding Gain (Loss), Total	$ (181,818)	$ 48,738

Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

No definition available.

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration