Fair Value of Financial Information - Measurements of Assets and Liabilities on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Assets:
Restricted funds	$ 34	$ 32
Rabbi trust investments	22	21
Deposits	8	7
Contingent cash payment from the sale of HOS		72
Mark-to-market derivative asset		1
Total assets	236	347
Liabilities:
Deferred compensation obligations	27	24
Mark-to-market derivative liability	8
Total liabilities	35	24
Total assets	201	323
Fixed-Income Securities
Assets:
Other investments	146	153
Money market and other
Assets:
Other investments	26	61
Level 1
Assets:
Restricted funds	34	32
Rabbi trust investments	22	21
Deposits	8	7
Contingent cash payment from the sale of HOS		0
Mark-to-market derivative asset		0
Total assets	230	268
Liabilities:
Deferred compensation obligations	27	24
Mark-to-market derivative liability	0
Total liabilities	27	24
Total assets	203	244
Level 1 | Fixed-Income Securities
Assets:
Other investments	140	147
Level 1 | Money market and other
Assets:
Other investments	26	61
Level 2
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Contingent cash payment from the sale of HOS		0
Mark-to-market derivative asset		1
Total assets	6	7
Liabilities:
Deferred compensation obligations	0	0
Mark-to-market derivative liability	8
Total liabilities	8	0
Total assets	(2)	7
Level 2 | Fixed-Income Securities
Assets:
Other investments	6	6
Level 2 | Money market and other
Assets:
Other investments	0	0
Level 3
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Contingent cash payment from the sale of HOS		72
Mark-to-market derivative asset		0
Total assets	0	72
Liabilities:
Deferred compensation obligations	0	0
Mark-to-market derivative liability	0
Total liabilities	0	0
Total assets	0	72
Level 3 | Fixed-Income Securities
Assets:
Other investments	0	0
Level 3 | Money market and other
Assets:
Other investments	$ 0	$ 0