Fair Value of Financial Instruments - Summary of Fair Value Information of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Interest and rent receivables, Book value	$ 81,965	$ 78,970
Loans, Book value	1,846,525	1,698,471
Debt, net Book value	(4,898,364)	(4,898,667)
Interest and rent receivables, Fair value	81,009	78,028
Loans, Fair value	1,871,705	1,722,101
Debt, net Fair value	$ (4,968,232)	$ (5,073,707)