Policyholder Account Balances, Future Policy Benefits and Claims - Amounts Recognized in Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	$ 182	$ 674
Interest Expense	98	388
Life Contingent Payout Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	66	196
Interest Expense	14	49
Term and Whole Life Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	42	169
Interest Expense	9	37
Disability Income Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	30	124
Interest Expense	8	32
Long Term Care Insurance
Liability for Future Policy Benefit, Activity [Line Items]
Gross Premiums	44	185
Interest Expense	$ 67	$ 270