Note 7 - Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Net carrying amount	$ 150,562
Franchise Rights [Member]
Gross carrying amount, indefinite-lived intangible assets	812,371	$ 812,137
Use Rights [Member]
Gross carrying amount, amortized intangible assets	3,828	4,138
Accumulated amortization	3,643	3,886
Net carrying amount	$ 185	$ 252
Customer Relationships [Member]
Useful life (Year)	14 years	14 years
Gross carrying amount, amortized intangible assets	$ 160,000	$ 160,000
Accumulated amortization	10,476	7,619
Net carrying amount	$ 149,524	$ 152,381
Trademarks and Trade Names [Member]
Useful life (Year)	2 years 255 days	2 years 255 days
Gross carrying amount, amortized intangible assets	$ 1,300	$ 1,300
Accumulated amortization	447	325
Net carrying amount	$ 853	$ 975
Minimum [Member] | Use Rights [Member]
Useful life (Year)	1 year	1 year
Maximum [Member] | Use Rights [Member]
Useful life (Year)	25 years	25 years