Real Estate and Loans Receivable - Assets Acquired (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Loans repaid	$ 193,262	$ 385,851
Intangible Lease Assets - Subject to Amortization [Member]
Business Acquisition [Line Items]
Weighted average useful life of acquired intangible lease assets (in years)	28 years 6 months	30 years	18 years 2 months 12 days
Capella [Member]
Business Acquisition [Line Items]
Loans repaid	$ 93,300
Median [Member]
Business Acquisition [Line Items]
Loans repaid		$ 385,900
Prime [Member]
Business Acquisition [Line Items]
Loans repaid	$ 100,000