Note 3 - Acquisitions (Details Textual) - USD ($)				3 Months Ended	6 Months Ended
	Nov. 12, 2019	Aug. 08, 2019	Apr. 01, 2019	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Nov. 11, 2019	Aug. 07, 2019	Mar. 31, 2019
Payment for Contingent Consideration Liability, Financing Activities					$ 483,000	$ (0)
Business Combination, Contingent Consideration, Liability, Total				$ 388,000	388,000		$ 1,900,000
Goodwill, Ending Balance				33,506,000	33,506,000			$ 33,637,000
Equity Method Investments				41,000	$ 41,000
SAVSU [Member]
Equity Method Investments		$ 5,800,000
Astero [Member]
Payments to Acquire Businesses, Gross			$ 12,521,000
Payments to Acquire Businesses, Initial Cash Payment			8,000,000.0
Payments to Acquire Businesses, Deferred Cash Payment			4,500,000
Business Combination, Consideration Transferred, Liabilities Incurred			1,491,000
Payment for Contingent Consideration Liability, Financing Activities				$ 483,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			8,500,000
Business Combination, Contingent Consideration, Liability, Total			1,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets			324,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets			4,100,000
Goodwill, Ending Balance			9,500,000								$ 9,515,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount			1,100,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total											$ 13,941,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			4,120,000
Astero [Member] | Earnout Payments Payable in Each Calendar Years of 2019, 2020 and 2021 [Member]
Business Combination, Consideration Transferred, Liabilities Incurred			3,500,000
Astero [Member] | Earnout Payment for Calendar Year 2021 [Member]
Business Combination, Consideration Transferred, Liabilities Incurred			$ 5,000,000.0
SAVSU [Member]
Goodwill, Ending Balance		$ 19,500,000								$ 21,037,000
Business Combinations, Number of Shares Acquired (in shares)		8,616
Business Acquisition, Percentage of Voting Interests Acquired		55.60%
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares)		1,100,000
Share Price (in dollars per share)		$ 18.12
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		$ 19,932,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total		35,800,000								$ 35,850,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value		$ 15,900,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage		44.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net, Total		$ 10,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net		4,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		12,150,000
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination, Total		$ 35,800,000
CBS Acquisition [Member]
Payments to Acquire Businesses, Gross	$ 11,000,000
Payments to Acquire Businesses, Initial Cash Payment	11,000,000.0
Business Combination, Consideration Transferred, Liabilities Incurred	856,000
Goodwill, Ending Balance	3,100,000								$ 2,954,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	4,000,000.0
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net, Total									15,856,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Tangible Assets, Net	6,000,000.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	6,800,000								$ 6,790,000
Business Combination, Consideration Transferred, Excluding Contingent Consideration	15,000,000.0
Business Combination, Cash Holdback Escrow to Satisfy Indemnification Claims	550,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Escrow Holdback	3,000,000.0
CBS Acquisition [Member] | Earning Payments Payable in Each Calendar Year 2020, 2021, 2022, 2023, and 2024 [Member]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	$ 15,000,000.0