Intangible Assets and Liabilities - Narratives (Details) - USD ($) $ in Millions		3 Months Ended
	Feb. 02, 2017	Mar. 31, 2017	Mar. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Net amortization of intangibles		$ 12.9	$ 9.3
Below and above market rent intangibles
Finite-Lived Intangible Assets [Line Items]
Net amortization of intangibles		$ 18.8	$ 0.1
Real estate | Buffalo Grove, IL
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible asset, amount	$ 2.0
Finite lived intangible asset/liability, useful life		20 years