Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2025

Retirement Benefits [Abstract]

Schedule of Components of Net Cost (Benefit) for Pension and Other Postretirement Plans

Components of net cost (benefit) for pension and other postretirement plans
	Three months ended March 31,
($ in millions)	2025		2024
Pension benefits
Service cost	$	25	$	33
Interest cost	60		58
Expected return on plan assets	(78)		(77)
Costs and expenses	7		14
Remeasurement of projected benefit obligation	53		(25)
Remeasurement of plan assets	23		25
Remeasurement (gains) losses	76		—
Pension net cost	$	83	$	14
Postretirement benefits
Service cost	$	—	$	—
Interest cost	2		2
Costs and expenses	2		2
Remeasurement of benefit obligation	2		(2)
Remeasurement of plan assets	—		—
Remeasurement (gains) losses	2		(2)
Postretirement net cost	$	4	$	—
Pension and postretirement benefits
Costs and expenses	$	9	$	16
Remeasurement (gains) losses	78		(2)
Total net cost	$	87	$	14

Schedule of Pension and Postretirement Benefits Remeasurement Gains and Losses

Pension and postretirement benefits remeasurement gains and losses
	Three months ended March 31,
($ in millions)	2025		2024
Remeasurement of benefit obligation (gains) losses:
Discount rate	$	59	$	(41)
Other assumptions	(4)		14
Remeasurement of plan assets (gains) losses	23		25
Remeasurement (gains) losses	$	78	$	(2)