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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Employee Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2008
Defined Benefit Plans and Other Postretirement Benefit Plans
Minimum participant age to elect				40 years
Employer discretionary contribution amount	$ 26	$ 24	$ 22
Requisite service period	3 years
Actual percentage return on plan assets	11.80%	(8.90%)
Pension plan assets at fair value	$ 317	$ 332	397
Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Matching contribution to defined contribution plan	6.00%
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Percentage of increase decrease in benefit obligations discount rate	0.30%
Change In Net Benefit Cost Discount Rate Assumption	2.37%
Pension Plan \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Cash dividends paid (less than $1 million)	$ 1	1
Supplemental Employee Retirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Accrued employee benefit	$ 11	8
Percentage of increase decrease in benefit obligations discount rate	0.31%
Change In Net Benefit Cost Discount Rate Assumption	2.52%
Expected contribution by employer during 2023	$ 7
Top Hat Savings Plan - Mutual Funds and Common Equities
Defined Benefit Plans and Other Postretirement Benefit Plans
CFC Top Hat Savings Plan	67	57
Top Hat
Defined Benefit Plans and Other Postretirement Benefit Plans
CFC Top Hat Savings Plan	67	57
Top Hat \| Top Hat Savings Plan - Mutual Funds and Common Equities \| Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans
Employer discretionary contribution amount	$ 1	$ 1	$ 1
Employer Common Stock
Defined Benefit Plans and Other Postretirement Benefit Plans
Pension plan assets, shares	100,610	100,610
Pension plan assets, fair value	$ 10	$ 10
Employer Common Stock \| Sale of stock
Defined Benefit Plans and Other Postretirement Benefit Plans
Pension plan assets, shares		101,727
Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	90.00%
Pension plan assets at fair value	$ 269	$ 245
Equity Securities \| Information Technology Sector
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	29.00%
Equity Securities \| Financial Services Sector
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	19.00%
Equity Securities \| Industrial Sector
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	16.00%
Equity Securities \| Healthcare Sector
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	13.00%
Equity Securities \| All Remaining Sectors
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	10.00%
Fixed Maturities
Defined Benefit Plans and Other Postretirement Benefit Plans
Pension plan assets at fair value	$ 32	44
Fixed Maturities \| United States Government
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	7.00%
Pension plan assets at fair value	$ 22	31
Fixed Maturities \| States, Municipalities and Political Subdivisions
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	2.00%
Pension plan assets at fair value	$ 6	6
Fixed Maturities \| Domestic Corporate Debt Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Allocation percentage of investments	1.00%
Pension plan assets at fair value	$ 4	7
Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Pension plan assets at fair value	$ 16	$ 43