Policy Liabilities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Change in morality and lapse assumptions, remeasurement gain (loss)	$ 134,300	$ 46,300
Variances in expected experience, remeasurement gain (loss)	24,000	14,700	$ 53,600	$ 38,400
Life
Liability for Future Policy Benefit, Activity [Line Items]
Change in morality and lapse assumptions, remeasurement gain (loss)	130,900	56,800
Variances in expected experience, remeasurement gain (loss)	18,500	13,700
Expected future gross premiums	29,678,228	29,804,051	29,678,228	29,804,051
Expected future net premiums	11,856,124	12,406,270	11,856,124	12,406,270	$ 12,000,397	$ 11,757,317	$ 11,981,537	$ 12,342,307
Difference between expected future gross premiums and expected future net premiums	17,800,000	17,400,000	17,800,000	17,400,000
Health
Liability for Future Policy Benefit, Activity [Line Items]
Change in morality and lapse assumptions, remeasurement gain (loss)	3,400	(10,500)
Variances in expected experience, remeasurement gain (loss)	5,500	1,000
Expected future gross premiums	14,040,440	12,407,986	14,040,440	12,407,986
Expected future net premiums	7,518,346	6,452,555	7,518,346	6,452,555	$ 6,627,718	$ 6,314,148	$ 6,007,794	$ 6,089,728
Difference between expected future gross premiums and expected future net premiums	$ 6,500,000	$ 5,900,000	$ 6,500,000	$ 5,900,000