Real Estate and Loans Receivable - Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Intangible lease assets	$ 443,134	$ 296,176
Intangible Assets [Member]
Debt Instrument [Line Items]
Intangible lease assets	443,000	296,000
Accumulated amortization, net	394,000	264,000
Amortization expense related to intangible lease assets	$ 15,800	$ 13,400	$ 9,100
Capitalized lease intangibles, weighted average life (in years)	24 years 3 months 19 days