Reserve for Future Policy Benefits and Contractholder Funds - Schedule of Key Assumptions used in Calculating the Reserve for Future Policy Benefits (Details)	Sep. 30, 2024	Sep. 30, 2023
Accident and health insurance
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average duration (in years)	8 years 3 months 18 days	4 years 3 months 18 days
Weighted-average interest rates
Interest accretion rate (discount rate at contract issuance)	5.05%	4.73%
Current discount rate (upper-medium grade fixed income yield)	4.65%	5.28%
Traditional life
Liability for Future Policy Benefit, Activity [Line Items]
Weighted-average duration (in years)	15 years 6 months	14 years 9 months 18 days
Weighted-average interest rates
Interest accretion rate (discount rate at contract issuance)	5.36%	5.43%
Current discount rate (upper-medium grade fixed income yield)	4.82%	5.56%