Revenue Recognition - Business Management Agreements with Managed Equity REITs (Details) - Managed Equity REITs - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Business Management and Incentive Fees
Business management fees as a percentage of transferred real estate assets			0.50%
Business management fees as a percentage of average invested capital below the threshold limit			0.70%
Maximum threshold amount for calculating the business management fees	$ 250,000		$ 250,000
Business management fees as a percentage of average invested capital above the threshold limit			0.50%
Minimum threshold amount for calculating the business management fees	250,000		$ 250,000
Business management fees as a percent of average market capitalization below the threshold limit			0.70%
Business management fees as a percent of average market capitalization above the threshold limit			0.50%
Aggregate base business management fees	$ 23,985	$ 22,573	$ 47,639	$ 44,128
Contingent incentive business management fee percentage			12.00%
Aggregate incentive business management fees					$ 0	$ 0