Insurance - Schedule of Actuarial Assumptions (Details)	Sep. 30, 2026	Sep. 30, 2025
Term and Whole Life \| Measurement Input, Mortality Rate, Expected
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0038	0.0039
Term and Whole Life \| Measurement Input, Mortality Rate, Actual
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0037	0.0040
Term and Whole Life \| Measurement Input, Lapses, Expected
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0375	0.0333
Term and Whole Life \| Measurement Input, Lapses, Actual
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0398	0.0356
Accidental Death and Disability Protection \| Measurement Input, Mortality Rate, Expected
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0002	0.0001
Accidental Death and Disability Protection \| Measurement Input, Mortality Rate, Actual
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0001	0.0001
Accidental Death and Disability Protection \| Measurement Input, Lapses, Expected
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0160	0.0170
Accidental Death and Disability Protection \| Measurement Input, Lapses, Actual
Market Risk Benefit [Line Items]
Market risk benefit, measurement input	0.0292	0.0218