Real Estate and Lending Activities - Assets Acquired (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition [Line Items]
Total assets acquired	$ 213,100	$ 2,020,198
Loans repaid	(93,262)	(385,851)
Total net assets acquired	119,838	1,634,347
Land and Land Improvements [Member]
Business Acquisition [Line Items]
Total assets acquired	13,874	113,309
Building [Member]
Business Acquisition [Line Items]
Total assets acquired	125,472	711,805
Intangible Lease Assets - Subject to Amortization [Member]
Business Acquisition [Line Items]
Total assets acquired	10,754	144,900
Net Investments in Direct Financing Leases [Member]
Business Acquisition [Line Items]
Total assets acquired	$ 63,000	170,700
Other Loans [Member]
Business Acquisition [Line Items]
Total assets acquired		514,484
Mortgage Loans [Member]
Business Acquisition [Line Items]
Total assets acquired		$ 365,000