Commitments and Contingencies - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
General liability insurance limit	$ 200.0
Property and rental value insurance coverage limit	2,000.0
Terrorist acts insurance coverage limit	2,000.0
Nuclear, biological, chemical, and radiological terrorism insurance limit	2,000.0
Additional capital funding committed amount	50.6
Real Estate Properties [Line Items]
Purchase obligation	707.8
Consolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	611.1
Principal payment guarantees	89.0
Unconsolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	96.7
Principal payment guarantees	$ 63.8