Revenue Recognition - Business Management Fees (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Jan. 31, 2020	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Managed Operators, ABP Trust and AIC
Related Party Transaction [Line Items]
Business management fee percent based on management agreements	0.50%		0.60%
Aggregate business management fees		$ 5,963		$ 7,145	$ 19,626	$ 21,292
AIC
Related Party Transaction [Line Items]
Business management fee percent based on total premiums paid						3.00%
Open End Fund
Related Party Transaction [Line Items]
Management fee as a percent of NAV					1.00%