Note 7 - Investment and Advances in Real Estate Joint Ventures - Investment and Advances to Real Estate Joint Ventures - Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
KIR [Member]
Assets	$ 872.3	$ 947.2
Members’ capital	300.0	275.7
Total Liabilities and Partners'/Members Capital	872.3	947.2
Excluding KIR and Rio Can [Member]
Assets	2,737.2	2,853.9
Members’ capital	1,621.9	1,663.6
Total Liabilities and Partners'/Members Capital	2,737.2	2,853.9
Noncontrolling interests	17.7	16.8
Real Estate [Member] | KIR [Member]
Assets	788.7	848.7
Real Estate [Member] | Excluding KIR and Rio Can [Member]
Assets	2,596.9	2,725.4
Other Assets [Member] | KIR [Member]
Assets	83.6	98.5
Other Assets [Member] | Excluding KIR and Rio Can [Member]
Assets	140.3	128.5
Notes Payable [Member] | KIR [Member]
Liabilities	0.0	73.0
Notes Payable [Member] | Excluding KIR and Rio Can [Member]
Liabilities	199.8	199.7
Mortgages Payable [Member] | KIR [Member]
Liabilities	556.0	578.5
Mortgages Payable [Member] | Excluding KIR and Rio Can [Member]
Liabilities	838.3	931.4
Other Liabilities [Member] | KIR [Member]
Liabilities	16.3	20.0
Other Liabilities [Member] | Excluding KIR and Rio Can [Member]
Liabilities	$ 59.5	$ 42.4