Real Estate and Loans Receivable - Concentration of Credit Risks and Related Party Transactions - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Acquisitions and Disposals [Line Items]
Revenues	$ 82,106,000	$ 80,777,000	$ 76,560,000	$ 73,089,000	$ 67,679,000	$ 60,106,000	$ 57,124,000	$ 57,614,000	$ 312,532,000	$ 242,523,000	$ 198,125,000
European [Member]
Significant Acquisitions and Disposals [Line Items]
Revenues									26,000,000	1,800,000
Related Party Transactions [Member]
Significant Acquisitions and Disposals [Line Items]
Lease and interest revenue earned from tenants									$ 101,800,000	$ 70,000,000	$ 54,300,000
Concentration of Credit Risks [Member] | Median Transaction [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of total assets accounted									11.30%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Ernest Health, Inc [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									18.30%	20.20%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Prime Health Care Services [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									26.90%	32.00%
Assets, Total [Member]
Significant Acquisitions and Disposals [Line Items]
Number of investment in property	0								0
Maximum percentage of entity's total assets invested on single property	4.00%								4.00%
Assets, Total [Member] | Customer Concentration Risk [Member] | Ernest Health, Inc [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									13.00%	15.90%
Assets, Total [Member] | Customer Concentration Risk [Member] | Prime Health Care Services [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									20.00%	24.50%
Assets, Total [Member] | Geographic Concentration Risk [Member] | California [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									14.60%	18.70%
Assets, Total [Member] | Geographic Concentration Risk [Member] | Texas [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									20.20%	22.70%
Assets, Total [Member] | Geographic Concentration Risk [Member] | European [Member]
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									20.00%	9.00%
Assets, Total [Member] | Geographic Concentration Risk [Member] | United States
Significant Acquisitions and Disposals [Line Items]
Percentage of entity revenue from affiliates									80.00%