Real Estate and Lending Activities - Summary of Status Update on Current Development Projects (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Business Acquisition [Line Items]
Commitment	$ 180,562
Costs Incurred as of June 30, 2018	47,620
Circle Health [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	44,825
Costs Incurred as of June 30, 2018	$ 20,942
Estimated Completion Date	1Q 2019
Circle Health Rehabilitation [Member] | Birmingham, England [Member]
Business Acquisition [Line Items]
Commitment	$ 22,269
Costs Incurred as of June 30, 2018	$ 3,360
Estimated Completion Date	3Q 2019
Surgery Partners [Member] | Idaho Falls, ID [Member]
Business Acquisition [Line Items]
Commitment	$ 113,468
Costs Incurred as of June 30, 2018	$ 23,318
Estimated Completion Date	1Q 2020