Note 13 - Goodwill and Other Intangible Assets - Identifiable Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-lived intangible assets, gross	$ 139.8	$ 86.0
Less accumulated amortization	(33.3)	(20.9)
Total identifiable intangible assets, net	106.5	65.1
Customer Relationships [Member]
Finite-lived intangible assets, gross	$ 118.6	75.3
Weighted average amortization period (Year)	11 years 6 months
Noncompete Agreements [Member]
Finite-lived intangible assets, gross	$ 6.9	0.2
Weighted average amortization period (Year)	6 years 9 months 18 days
Trade Names [Member]
Finite-lived intangible assets, gross	$ 3.8	0.0
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