Commitments and Contingencies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate Properties [Line Items]
General liability insurance limit	$ 200,000,000
Property and rental value insurance coverage limit	2,000,000,000.0
Terrorist acts insurance coverage limit	2,000,000,000
Purchase obligation	766,000,000
Additional capital funding committed amount	49,300,000
Rental expense related to non-cancelable operating and capital leases	4,700,000	$ 2,100,000	$ 1,900,000
Consolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	676,000,000
Principal payment guarantees	91,500,000
Unconsolidated Properties
Real Estate Properties [Line Items]
Purchase obligation	90,000,000
Principal payment guarantees	$ 31,000,000
Minimum
Real Estate Properties [Line Items]
Commitment amortization period	2 years
Minimum | Unconsolidated Properties
Real Estate Properties [Line Items]
Commitment amortization period	2 years
Maximum
Real Estate Properties [Line Items]
Commitment amortization period	3 years
Maximum | Unconsolidated Properties
Real Estate Properties [Line Items]
Commitment amortization period	3 years