Note 6 - Stockholders' Equity (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2012
Excess Stock, Shares Authorized	1,000,000
Preferred Stock, Shares Outstanding, Ending Balance	0
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total	43,000
Stock Repurchased During Period, Value	$ 133,000	$ 136,000
Minimum [Member]
Equity Method Investment, Ownership Percentage			4.90%
Common Stock [Member]
Stock Repurchased During Period, Shares	(268,000)	(163,000)
Stock Repurchased During Period, Value	$ 4,000
Privately Negotiated Transaction [Member] | Common Stock [Member]
Stock Repurchased During Period, Shares	221,121	0
Stock Repurchased During Period, Value	$ 133,000
Stock Repurchase Program, Authorized Amount				$ 5,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 2,800,000
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	225,000
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total		0
Restricted Stock [Member]
Stock Repurchased During Period, Shares	46,643	163,214
Stock Repurchased During Period, Value	$ 30,000	$ 135,000