Real Estate and Lending Activities - Concentrations of Credit Risk - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) Investment	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Investment	Sep. 30, 2014 USD ($)	Dec. 31, 2014
Business Acquisition [Line Items]
Revenue	$ 114,570	$ 80,777	$ 310,333	$ 230,426
Assets, Total [Member] | Customer Concentration Risk [Member]
Business Acquisition [Line Items]
Number of investment in property | Investment	0		0
Maximum percentage of entity's total assets invested on single property	2.00%		2.00%
Assets, Total [Member] | Customer Concentration Risk [Member] | Median Kliniken [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			13.20%		11.30%
Assets, Total [Member] | Customer Concentration Risk [Member] | Capella Healthcare Inc [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			17.60%
Assets, Total [Member] | Geographic Concentration Risk [Member] | United States [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			80.00%		80.00%
Assets, Total [Member] | Geographic Concentration Risk [Member] | European [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			20.00%		20.00%
Assets, Total [Member] | Geographic Concentration Risk [Member] | California [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			9.70%		14.60%
Assets, Total [Member] | Geographic Concentration Risk [Member] | Texas [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			15.90%		20.20%
Sales Revenue, Net [Member] | European [Member]
Business Acquisition [Line Items]
Revenue	$ 25,500	$ 6,500	$ 59,900	$ 17,400
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Median Kliniken [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates	16.10%		12.40%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Capella Healthcare Inc [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates	6.20%		2.30%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Ernest Health, Inc [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates	14.10%	18.30%	14.80%	18.70%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Prime Health Care Services [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates	22.80%	26.40%	24.50%	27.80%
Asset Leased [Member] | Customer Concentration Risk [Member] | Ernest Health, Inc [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			6.00%		7.70%
Asset Leased [Member] | Customer Concentration Risk [Member] | Prime Health Care Services [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			10.40%		12.60%
Loaned To Ernest [Member] | Customer Concentration Risk [Member] | Ernest Health, Inc [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			3.80%		5.30%
Loaned to Prime [Member] | Customer Concentration Risk [Member] | Prime Health Care Services [Member]
Business Acquisition [Line Items]
Percentage of entity revenue from affiliates			7.70%		7.40%