Note 1 - Description of Business and Significant Accounting Policies (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2021 $ / shares shares	Jun. 30, 2020 shares	Jun. 30, 2021 $ / shares shares	Jun. 30, 2020 shares	Dec. 31, 2020 $ / shares shares
Number of Wholly-Owned Operating Subsidiaries	5		5
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares	$ 0.10		$ 0.10		$ 0.10
Common Stock, Shares Authorized (in shares)	20,000,000		20,000,000		20,000,000
Common Stock, Shares, Issued, Total (in shares)	7,745,404		7,745,404		7,741,487
Common Stock, Shares, Outstanding, Ending Balance (in shares)	7,745,404		7,745,404		7,741,487
Weighted Average Number of Shares Outstanding, Basic and Diluted (in shares)	7,743,517	7,741,272	7,742,384	7,737,418