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, 2017	Sep. 30, 2018	Sep. 30, 2017
Disposal Group Not Discontinued Operation Income Statement Disclosures [Abstract]
Revenues	[1]	$ 20,115	$ 35,846	$ 88,838	$ 95,320
Real estate depreciation and amortization	[2]	(237)	(8,786)	(15,849)	(23,092)
Property-related expenses		(265)	(388)	(531)	(394)
Other	[3]	692,362	(3,303)	715,246	(11,211)
Income from real estate dispositions, net		$ 711,975	$ 23,369	$ 787,704	$ 60,623

[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] Lower in 2018 as we stopped depreciation on properties once deemed held for sale, such as with the 71 properties on June 30, 2018.

[3] Includes $695.2 million of gains on sale for the three months ended September 30, 2018 and $719.4 million for the nine months ended September 30, 2018