Summary of Fair Value Estimates for Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest and rent receivables	$ 45,289		$ 29,862
Loans	334,693	[1]	239,839	[1]
Debt, net	(1,025,160)		(689,849)
Estimate of Fair Value, Fair Value Disclosure
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest and rent receivables	36,700		22,866
Loans	335,595	[1]	243,272	[1]
Debt, net	$ (1,082,333)		$ (688,032)

[1] Excludes loans related to Ernest Transaction since they are recorded at fair value and discussed below.