Variable Interest Entities - Schedule of Variable Interest Entities (Details) $ in Thousands	Sep. 30, 2018 USD ($)
VIE tenants-DFLs
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	$ 601,137
VIE tenants-operating leases
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	6,643
CCRC OpCo
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	180,174
Unconsolidated Development JVs
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	15,222
Loan - Seller Financing
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	10,000
CMBS and LLC investment
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	$ 34,133