Fair Value of Financial Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Carrying Value [Member]
Derivative [Line Items]
Notes and bonds payable	[1]	$ 1,418.3	$ 1,425.0
Fair Value [Member]
Derivative [Line Items]
Notes and bonds payable	[1]	$ 1,453.7	$ 1,439.0

[1] Level 3 - Fair value derived from valuation techniques in which one or more significant inputs or significant value drivers is unobservable.