Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2023

Employee Benefits

Schedule of Plans' assets measured at estimated fair value

	December 31,
(Millions of dollars)	2023		Level 1		Level 2		Level 3
Assets:
Domestic equity securities	$	81	$	81	$	—	$	—
Foreign equity securities		51		51		—		—
Domestic fixed income mutual funds		26		26		—		—
Foreign fixed income mutual funds		11		11		—		—
Money market funds		2		2		—		—
Total assets	$	171	$	171	$	—	$	—

	December 31,
(Millions of dollars)	2022		Level 1		Level 2		Level 3
Assets:
Domestic equity securities	$	84	$	84	$	—	$	—
Foreign equity securities		60		60		—		—
Domestic fixed income mutual funds		26		26		—		—
Foreign fixed income mutual funds		11		11		—		—
Money market funds		1		1		—		—
Total assets	$	182	$	182	$	—	$	—

Schedule of assumptions used in determining pension information for qualified and nonqualified plans

	Years ended December 31,
	2023		2022		2021
Weighted-average assumptions:
Discount rate used to determine obligations	5.26	%	5.38	%	2.78	%
Discount rate used to determine net periodic benefit cost	5.38	%	2.78	%	2.39	%
Expected return on plan assets	6.50	%	6.25	%	6.25	%
Long-term rate of increase in compensation levels	3.80	%	4.00	%	4.00	%

Schedule of aggregate changes in the benefit obligation and fair value of assets for the qualified and nonqualified plans and the funded status

						December 31,
						2023		2022
(Millions of dollars)		Assets exceed accumulated benefits		Accumulated benefits exceed assets		Total		Accumulated benefits exceed assets
Reconciliation of benefit obligation:
Benefit obligation at beginning of year	$	129	$	147	$	276	$	362
Service cost		3		3		6		9
Interest cost		7		6		13		10
Actuarial losses (gains)		(1)		2		1		(97)
Plan settlements		(21)		(25)		(46)		—
Benefits paid		(4)		(4)		(8)		(8)
Benefit obligation at end of year	$	113	$	129	$	242	$	276
Reconciliation of fair value of plan assets:
Fair value of plan assets at beginning of year	$	126	$	56	$	182	$	227
Actual return on plan assets		21		9		30		(38)
Employer contributions		—		13		13		1
Plan settlements		(21)		(25)		(46)		—
Benefits paid		(4)		(4)		(8)		(8)
Fair value of plan assets at end of year	$	122	$	49	$	171	$	182
Funded status	$	9	$	(80)	$	(71)	$	(94)

Schedule of net periodic benefit cost for all plans

	Years ended December 31,
(Millions of dollars)	2023		2022		2021
Components of net periodic benefit cost:
Service cost	$	6	$	9	$	10
Interest cost		13		10		9
Expected return on plan assets		(11)		(14)		(12)
Amortization		—		6		9
Settlement loss recognized		1		—		6
Net periodic benefit cost	$	9	$	11	$	22