Real Estate and Other Activities - Net Assets Acquired (Detail) - USD ($) $ in Thousands		Sep. 30, 2023	Sep. 30, 2022
Business Acquisition [Line Items]
Total assets acquired		$ 235,187	$ 972,243
Liabilities assumed			(25,727)
Loans repaid	[1]	(22,900)
Total net assets acquired		212,287	972,243
Land and Land Improvements [Member]
Business Acquisition [Line Items]
Total assets acquired		28,916	34,925
Building [Member]
Business Acquisition [Line Items]
Total assets acquired		114,966	312,645
Intangible Lease Assets [Member]
Business Acquisition [Line Items]
Total assets acquired		16,305	19,839
Mortgage Loans [Member]
Business Acquisition [Line Items]
Total assets acquired			100,000
Other Loans [Member]
Business Acquisition [Line Items]
Total assets acquired		25,000
Investments in Unconsolidated Real Estate Joint Ventures [Member]
Business Acquisition [Line Items]
Total assets acquired			399,456
Investments In Unconsolidated Operating Entities [Member]
Business Acquisition [Line Items]
Total assets acquired		$ 50,000	$ 131,105

[1] The 2023 column includes a $23 million mortgage loan that was converted to fee simple ownership of one property as described under Lifepoint Transaction below.