Real Estate and Lending Activities - Summary of Operations for Disposed Assets in 2018 (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2018	Sep. 30, 2018
Disposal Group Not Discontinued Operation Income Statement Disclosures [Abstract]
Revenues	[1]	$ 20,115	$ 88,838
Real estate depreciation and amortization		(237)	(15,849)
Property-related expenses		(265)	(531)
Other	[2]	692,362	715,246
Income from real estate dispositions, net		$ 711,975	$ 787,704

[1] Includes $2.5 million and $7.6 million of straight-line rent and other write-offs associated with the disposal transactions for the three and nine months ended September 30, 2018, respectively

[2] Includes $695.2 million of gains on sale for the three months ended September 30, 2018 and $719.3 million for the nine months ended September 30, 2018