Fair Value of Financial Information - Measurements of Assets and Liabilities on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Restricted funds	$ 39	$ 31
Rabbi trust investments	18	17
Deposits	4	3
Other investments	18	8
Total assets	79	59
Liabilities:
Deferred compensation obligations	23	21
Total liabilities	23	21
Total assets	56	38
Level 1
Assets:
Restricted funds	39	31
Rabbi trust investments	18	17
Deposits	4	3
Other investments	18	8
Total assets	79	59
Liabilities:
Deferred compensation obligations	23	21
Total liabilities	23	21
Total assets	56	38
Level 2
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Other investments	0	0
Total assets	0	0
Liabilities:
Deferred compensation obligations	0	0
Total liabilities	0	0
Total assets	0	0
Level 3
Assets:
Restricted funds	0	0
Rabbi trust investments	0	0
Deposits	0	0
Other investments	0	0
Total assets	0	0
Liabilities:
Deferred compensation obligations	0	0
Total liabilities	0	0
Total assets	$ 0	$ 0