Real Estate Activities - Summary of Status on Current Development Projects (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Commitment	$ 178,261
Costs Incurred as of December 31, 2018	84,172
Circle Health [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	43,288
Costs Incurred as of December 31, 2018	$ 28,881
Estimated Rent Commencement Date	2Q 2019
Circle Health Rehabilitation [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	$ 21,505
Costs Incurred as of December 31, 2018	$ 9,081
Estimated Rent Commencement Date	3Q 2019
Surgery Partners [Member] | Idaho Falls, ID [Member]
Business Acquisition [Line Items]
Commitment	$ 113,468
Costs Incurred as of December 31, 2018	$ 46,210
Estimated Rent Commencement Date	1Q 2020