Real Estate and Lending Activities - Net Assets Acquired (Detail) - USD ($) $ in Thousands		Sep. 30, 2020	Sep. 30, 2019
Business Acquisition [Line Items]
Total assets acquired		$ 3,524,910	$ 3,703,092
Liabilities assumed		(134,203)
Loans repaid	[1]	(737,242)
Total net assets acquired		2,787,668	3,703,092
Land and Land Improvements [Member]
Business Acquisition [Line Items]
Total assets acquired		330,941	375,721
Building [Member]
Business Acquisition [Line Items]
Total assets acquired		2,610,197	1,320,449
Intangible Lease Assets - Subject to Amortization [Member]
Business Acquisition [Line Items]
Total assets acquired		364,006	149,201
Investments in Financing Leases [Member]
Business Acquisition [Line Items]
Total assets acquired			1,386,797
Mortgage Loans [Member]
Business Acquisition [Line Items]
Total assets acquired		47,641	51,267
Equity Investments [Member]
Business Acquisition [Line Items]
Total assets acquired			284,399
Other Loans and Assets [Member]
Business Acquisition [Line Items]
Total assets acquired		$ 306,328	$ 135,258

[1] The 2020 column includes $737 million of loans advanced to Steward Health Care, Inc. (“Steward”) in 2017 and exchanged for the fee simple real estate of two hospitals as described below.