Note 13 - Notes Payable - Notes Payable (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Deferred financing costs, net		$ (47.7)		$ (31.4)
Balance, Net		3,927.3		3,761.3
Maximum [Member]
Interest Rate					7.00%
Unsecured Debt [Member]
Gross Balance		$ 3,400.0		$ 2,290.9
Unsecured Debt [Member] | Minimum [Member]
Interest Rate		2.70%		3.13%
Maturity Date		Oct-2019		May-2017
Unsecured Debt [Member] | Maximum [Member]
Interest Rate		6.88%		6.88%
Maturity Date		Dec-2046		Apr-2045
Medium-term Notes [Member]
Gross Balance		$ 300.0		$ 600.0
Medium-term Notes [Member] | Minimum [Member]
Interest Rate		4.30%		4.30%
Maturity Date		Feb-2018		Mar-2016
Medium-term Notes [Member] | Maximum [Member]
Interest Rate		4.30%		5.78%
Maturity Date		Feb-2018		Feb-2018
Term Loan [Member]
Gross Balance		$ 250.0	[1]	$ 650.0
Interest Rate		1.60%		1.37%
Term Loan [Member] | Minimum [Member]
Interest Rate	[1]
Maturity Date	[1]	Jan-2017		Jan-2017
Term Loan [Member] | Maximum [Member]
Interest Rate	[1]
Maturity Date	[1]	Jan-2017		Jan-2017
Line of Credit [Member]
Gross Balance	[2]	$ 25.0
Interest Rate		1.67%		1.35%
Line of Credit [Member] | Minimum [Member]
Interest Rate	[2]
Maturity Date	[2]	Mar-2018		Mar-2018 (b)
Line of Credit [Member] | Maximum [Member]
Interest Rate	[2]
Maturity Date	[2]	Mar-2018		Mar-2018 (b)
Canadian Notes Payable [Member]
Gross Balance				$ 251.8
Canadian Notes Payable [Member] | Minimum [Member]
Interest Rate				3.86%
Maturity Date				Apr-2018
Canadian Notes Payable [Member] | Maximum [Member]
Interest Rate				5.99%
Maturity Date				Aug-2020

[1] Interest rate is equal to LIBOR + 0.95% (1.60% and 1.37% at December 31, 2016 and 2015, respectively). During January 2017, the Company repaid the $250.0 million outstanding balance on the Term Loan and terminated the agreement.

[2] Interest rate is equal to LIBOR + 0.925% (1.67% and 1.35% at December 31, 2016 and 2015, respectively). During February 2017, the Company repaid the outstanding balance on the Credit Facility and terminated the agreement. The Company closed on a new $2.25 billion unsecured revolving credit facility which is scheduled to mature March 2021 with two six-month extension options at an interest rate of LIBOR plus 87.5 basis points.