Retirement and Employee Benefit Plans (Changes in Plans Benefit Obligations, Fair Value of Assets, and Funded Status) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Change in benefit obligations:
Benefit obligation at January 1		$ 57	$ 126
Service cost		0	0	$ 0
Interest cost		0	3	4
Actuarial gain		0	(29)
Benefits paid		0	(2)
Plan amendments		0	(2)
Settlements		(57)	(39)
Benefit obligation at December 31		0	57	126
Change in plan assets:
Fair value of plan assets at January 1		72	114
Actual return on plan assets		0	0
Employer contributions		0	0
Benefits paid		0	(2)
Settlements		(58)	(40)
Transfer to qualified replacement plan	$ (14)	(14)	0
Fair value of plan assets at December 31		0	72	114
Funded status of plans at December 31		0	15
Other Postretirement Benefits
Change in benefit obligations:
Benefit obligation at January 1		9	13
Service cost		2	2	2
Interest cost		1	0	0
Actuarial gain		(7)	(5)
Benefits paid		0	(1)
Plan amendments		0	0
Settlements		0	0
Benefit obligation at December 31		5	9	13
Change in plan assets:
Fair value of plan assets at January 1		0	0
Actual return on plan assets		0	0
Employer contributions		0	1
Benefits paid		0	(1)
Settlements		0	0
Transfer to qualified replacement plan		0		0
Fair value of plan assets at December 31		0	0	$ 0
Funded status of plans at December 31		$ (5)	$ (9)