Note 13 - Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-lived intangible assets, gross	$ 153.9	$ 139.8
Less accumulated amortization	(47.1)	(33.3)
Total identifiable intangible assets, net	106.8	106.5
Customer Relationships [Member]
Finite-lived intangible assets, gross	$ 131.7	118.6
Weighted average amortization period (Year)	11 years
Noncompete Agreements [Member]
Finite-lived intangible assets, gross	$ 7.9	6.9
Weighted average amortization period (Year)	6 years 7 months 6 days
Trade Names [Member]
Finite-lived intangible assets, gross	$ 3.8	3.8
Weighted average amortization period (Year)	2 years
LDC Network Access [Member]
Finite-lived intangible assets, gross	$ 10.5	$ 10.5
Weighted average amortization period (Year)	10 years