Real Estate and Lending Activities - Assets Acquired (Parenthetical) (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Loans repaid	$ 93,262	$ 385,851
Intangible Lease Assets - Subject to Amortization [Member]
Business Acquisition [Line Items]
Weighted average useful life of acquired intangible lease assets (in years)	19 years 4 months 24 days	28 years 4 months 24 days
Capella [Member]
Business Acquisition [Line Items]
Loans repaid	$ 93,262
Median [Member]
Business Acquisition [Line Items]
Loans repaid		$ 385,851