List of Assets Purchased and Invested as Part of Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Significant Acquisitions and Disposals [Line Items]
Total assets acquired	$ 606,500	$ 223,505
Total liabilities assumed		(14,592)
Net assets acquired	606,500	208,913
Land
Significant Acquisitions and Disposals [Line Items]
Total assets acquired		17,218
Building
Significant Acquisitions and Disposals [Line Items]
Total assets acquired		178,535
Intangible Lease Assets
Significant Acquisitions and Disposals [Line Items]
Total assets acquired		15,351
Net Investment in Direct Financing Leases
Significant Acquisitions and Disposals [Line Items]
Total assets acquired	310,000
Mortgage Loans
Significant Acquisitions and Disposals [Line Items]
Total assets acquired	200,000
Other loans
Significant Acquisitions and Disposals [Line Items]
Total assets acquired	93,200	7,233
Equity Investments
Significant Acquisitions and Disposals [Line Items]
Total assets acquired	$ 3,300	$ 5,168