Note 10 - Commitments and Contingencies - Summary of Concentration Risk by Segment (Details) - Total Revenue [Member] - Geographic Concentration Risk [Member] - New York City [Member]	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Year ended December 31, 2019	100.00%	100.00%	100.00%
Commercial Segment [Member]
Year ended December 31, 2019	25.00%	26.00%	28.00%
Residential Segment [Member]
Year ended December 31, 2019	75.00%	74.00%	72.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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