Variable Interest Entities - Schedule of Variable Interest Entities (Details) $ in Thousands	Mar. 31, 2018 USD ($)
VIE tenants-DFLs
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	$ 600,822
VIE tenants-operating leases
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	5,983
CCRC OpCo
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	190,662
RIDEA II
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	309,882
Unconsolidated Development JVs
Variable Interest Entity [Line Items]
Maximum Loss Exposure and Carrying Amount	13,070
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	$ 33,874