Note 5 - Acquisitions (Details Textual) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Number of Businesses Acquired	6	15
Business Combination, Acquisition Related Costs	$ 4,561	$ 8,042
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability		(962)
Business Acquisition, Goodwill, Expected Tax Deductible Amount	34,661	6,911
Business Combination, Contingent Consideration, Liability, Total	24,128
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	22,286
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	26,219
Contingent Consideration Paid	4,664	10,056
Fair Value, Inputs, Level 3 [Member]
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(261)	(503)
Business Combination, Contingent Consideration, Liability, Total	$ 24,128	$ 14,423
FirstService Residential Segment [Member]
Number of Businesses Acquired	2	3
FirstService Brands Segment [Member]
Number of Businesses Acquired		12
FirstService Brands Segment [Member] \| Independent Restoration Companies [Member]
Number of Businesses Acquired		5
FirstService Brands Segment [Member] \| California Closets [Member]
Number of Businesses Acquired		3
FirstService Brands Segment [Member] \| Fire Protection Operations [Member]
Number of Businesses Acquired		2
FirstService Brands Segment [Member] \| Fire Protection [Member]
Number of Businesses Acquired	2
FirstService Brands Segment [Member] \| Independent Restoration [Member]
Number of Businesses Acquired	2

The contingent consideration paid.

No definition available.

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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

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For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

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Amount of liability recognized arising from contingent consideration in a business combination.

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The number of businesses acquired by the entity during the period.

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