Revenue Recognition - Managed Equity REITs (Details) - Managed Equity REITs - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 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	$ 22,573	$ 24,527	$ 44,128	$ 51,918
Contingent incentive business management fee percentage			12.00%