Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2024

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)	2024		2023
Pension benefits
Service cost	$	33	$	33
Interest cost	58		60
Expected return on plan assets	(77)		(77)
Amortization of prior service credit	—		—
Costs and expenses	14		16
Remeasurement of projected benefit obligation	(25)		123
Remeasurement of plan assets	25		(180)
Remeasurement (gains) losses	—		(57)
Pension net cost (benefit)	$	14	$	(41)
Postretirement benefits
Service cost	$	—	$	—
Interest cost	2		3
Amortization of prior service credit	—		(6)
Costs and expenses	2		(3)
Remeasurement of projected benefit obligation	(2)		4
Remeasurement of plan assets	—		—
Remeasurement (gains) losses	(2)		4
Postretirement net cost	$	—	$	1
Pension and postretirement benefits
Costs and expenses	$	16	$	13
Remeasurement (gains) losses	(2)		(53)
Total net cost (benefit)	$	14	$	(40)

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)	2024		2023
Remeasurement of projected benefit obligation (gains) losses:
Discount rate	$	(41)	$	124
Other assumptions	14		3
Remeasurement of plan assets (gains) losses	25		(180)
Remeasurement (gains) losses	$	(2)	$	(53)