Note 2 - Other Assets (Details Textual) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Capitalized Computer Software, Accumulated Amortization	$ 17,400,000
Goodwill and Intangible Asset Impairment	0	$ 0	$ 0
Other Assets [Member]
Indefinite-Lived Franchise Rights	7,000,000		$ 7,000,000
Computer Software, Intangible Asset [Member]
Interest Costs Capitalized	$ 32,200,000
Finite-Lived Intangible Asset, Useful Life	15 years
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 3,400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3,400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3,400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3,400,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	3,400,000
Computer Software, Intangible Asset [Member] | Depreciation and Amortization [Member]
Amortization of Intangible Assets	$ 900,000	$ 800,000