Note 8 - Common Stock (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 shares	Sep. 30, 2019 shares	Sep. 30, 2020 shares	Sep. 30, 2019 shares	Dec. 31, 2019 shares
Bold Contribution Agreement [Member] | Member Units [Member]
Stockholders Equity, Conversion Ratio			1
Common Class A [Member]
Common Stock, Shares, Issued, Total (in shares)	30,210,749		30,210,749		29,421,131
Common Stock, Shares, Outstanding, Ending Balance (in shares)	30,210,749		30,210,749		29,421,131
Common Class A [Member] | Bold Contribution Agreement [Member]
Stockholders Equity, Conversion Ratio			1
Common Class A [Member] | The 2014 Plan [Member]
Stock Issued During Period, Shares, New Issues (in shares)	195,344	167,827	726,082	569,883
Treasury Stock, Shares, Acquired (in shares)	54,268	49,111	187,773	151,716
Common Class B [Member]
Common Stock, Shares, Issued, Total (in shares)	35,009,371		35,009,371		35,260,680
Stock Issued During Period, Shares, Conversion of Convertible Securities (in shares)	49,316	35,732	251,309	35,732
Common Stock, Shares, Outstanding, Ending Balance (in shares)	35,009,371		35,009,371		35,260,680