Note 13 - Mortgages and Construction Loan Payable (Details Textual) $ in Millions	1 Months Ended	12 Months Ended
Aug. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Long-term Debt, Total		$ 4,831.8	$ 4,381.5
Gain (Loss) on Forgiveness of Debt			4.3
Accrued Interest Extinguished			3.4
Debt Instrument, Unamortized Discount (Premium), Net, Total		7.9
Debt Issuance Costs, Net, Total		$ 1.5
Construction Loans [Member]
Debt Instrument, Commitment	$ 67.0
Debt Instrument, Interest Rate, Effective Percentage		3.56%
Long-term Debt, Total		$ 67.0
Construction Loans [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	1.80%
Mortgage Debt Encumbered Operating Property [Member]
Repayments of Long-term Debt, Total		6.6
Debt Instrument, Increase (Decrease), Net, Total		(7.0)
Liabilities, Fair Value Adjustment		(0.1)
Debt Instrument, Decrease, Forgiveness		2.8
Mortgages [Member]
Long-term Debt, Total		484.0	492.4
Deconsolidation of Mortgage Loans			206.0
Long-term Debt, Fair Value		7.9	13.1
Real Estate Disposed of Through Foreclosure			12.4
Debt Issuance Costs, Net, Total		$ 1.5	2.5
Mortgages [Member] \| Encumbered Operating Properties [Member]
Repayments of Long-term Debt, Total			205.6
Long-term Debt, Fair Value			$ 0.9
Number of Real Estate Properties			6

The amount of accrued interest extinguished.

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The amount of debt instrument that has been committed under a certain agreement.

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No definition available.

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The amount of mortgage loans deconsolidated.

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The amount of gain (loss) on forgiveness of debt.

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Carrying amount as of the balance sheet date of land and buildings disposed of through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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No definition available.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Decrease for amounts of indebtedness forgiven by the holder of the debt instrument.

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Net increase or decrease in the carrying amount of the debt instrument for the period.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

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No definition available.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The number of real estate properties owned as of the balance sheet date.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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