Real Estate and Lending Activities - Assets Acquired (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Total assets acquired	$ 3,703,092	$ 1,166,618
Loans repaid		(525,426)
Total net assets acquired	3,703,092	641,192
Mortgage Loans [Member]
Business Acquisition [Line Items]
Total assets acquired	51,267
Investment in sale/leaseback transactions [Member]
Business Acquisition [Line Items]
Total assets acquired	1,386,797
Other Loans [Member]
Business Acquisition [Line Items]
Total assets acquired	135,258	336,458
Land and Land Improvements [Member]
Business Acquisition [Line Items]
Total assets acquired	375,721	57,452
Building [Member]
Business Acquisition [Line Items]
Total assets acquired	1,320,449	467,164
Intangible Lease Assets - Subject to Amortization [Member]
Business Acquisition [Line Items]
Total assets acquired	149,201	60,277
Equity Investments [Member]
Business Acquisition [Line Items]
Total assets acquired	$ 284,399	$ 245,267