Note 11 - Interest Rate Swaps (Details Textual) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Derivative Liability, Total	$ 89.7
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax, Parent, Total	(89.7)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent, Total	(67.5)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	11.0
Interest Expense [Member]
Settlement of Swap Payments	3.1
First Interest Rate Swap Agreement [Member] \| Cash Flow Hedging [Member]
Derivative, Notional Amount	$ 850.0
Derivative, Fixed Interest Rate	2.653%
Second Interest Rate Swap Agreement [Member] \| Cash Flow Hedging [Member]
Derivative, Notional Amount	$ 350.0
Derivative, Fixed Interest Rate	2.739%

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