Note 2 - Summary of Significant Accounting Policies - Weighted Average Common Shares (Details) - shares	3 Months Ended										12 Months Ended
	Dec. 31, 2017	[1],[2]	Sep. 30, 2017	[3]	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Weighted average common shares outstanding - basic (in shares)	10,308,243		10,288,325		10,277,155	10,264,565	10,273,702	10,295,447	10,295,836	10,390,002	10,284,572	10,313,747
Potentially dilutive securities:
Unvested shares of restricted stock and employee stock options (in shares)											54,741	19,173
Weighted average common shares outstanding - diluted (in shares)	10,308,243		10,351,009		10,334,894	10,295,337	10,297,439	10,318,715	10,310,692	10,404,244	10,339,313	10,332,920
Average number of potentially dilutive securities excluded from calculation (in shares)											77,047	18,658

[1] The quarter ended December 31, 2017 includes a $7,525 increase in the fair value of contingent consideration, which was not deductible for tax purposes.

[2] The quarter ended December 31, 2017 includes adjustments related to tax legislation enacted in December 2017, as discussed in Note 2 and 11.

[3] The quarter ended September 30, 2017 includes a $549 reduction in the fair value of contingent consideration, which was not taxable.