Real Estate and Lending Activities - Summary of Status Update on Current Development Projects (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Business Acquisition [Line Items]
Commitment	$ 179,688
Costs Incurred as of March 31, 2019	102,239
Circle Health [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	44,241
Costs Incurred as of March 31, 2019	$ 34,705
Estimated Rent Commencement Date	3Q 2019
Circle Health Rehabilitation [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	$ 21,979
Costs Incurred as of March 31, 2019	$ 11,677
Estimated Rent Commencement Date	3Q 2019
Surgery Partners [Member] | Idaho Falls, ID [Member]
Business Acquisition [Line Items]
Commitment	$ 113,468
Costs Incurred as of March 31, 2019	$ 55,857
Estimated Rent Commencement Date	1Q 2020