Employee Benefit Plans - PAC - Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Postretirement
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 614	$ 769	$ 744
Other Postretirement | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	482	607
Other Postretirement | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	337	437
Other Postretirement | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	145	170
Other Postretirement | Cash equivalents | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	24	16
Other Postretirement | Cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	15	12
Other Postretirement | Cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	9	4
Other Postretirement | U.S. government obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	8	27
Other Postretirement | U.S. government obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	8	27
Other Postretirement | U.S. government obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | Corporate obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	52	85
Other Postretirement | Corporate obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | Corporate obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	52	85
Other Postretirement | Municipal obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	35	43
Other Postretirement | Municipal obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | Municipal obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	35	43
Other Postretirement | Agency, asset and mortgage-backed obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	49	38
Other Postretirement | Agency, asset and mortgage-backed obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | Agency, asset and mortgage-backed obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	49	38
Other Postretirement | Equity securities, U.S. companies | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	7	4
Other Postretirement | Equity securities, U.S. companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	7	4
Other Postretirement | Equity securities, U.S. companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 0	$ 0
Other Postretirement | Investment funds
Defined Benefit Plan Disclosure [Line Items]
Percentage of funds comprised of equity securities	55.00%	55.00%
Percentage of funds comprised of debt securities	45.00%	45.00%
Percentage of funds invested in United States securities	88.00%	88.00%
Percentage of funds invested in international securities	12.00%	12.00%
Other Postretirement | Investment funds | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 307	$ 394
Other Postretirement | Investment funds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	307	394
Other Postretirement | Investment funds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | Investment funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	132	161
Other Postretirement | Limited partnership interests | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	1
Other Postretirement | PAC
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	264	324	327
Other Postretirement | PAC | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	132	162
Other Postretirement | PAC | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	18	32
Other Postretirement | PAC | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	114	130
Other Postretirement | PAC | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Cash equivalents | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	10	5
Other Postretirement | PAC | Cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	5	4
Other Postretirement | PAC | Cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	5	1
Other Postretirement | PAC | Cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | U.S. government obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	6	24
Other Postretirement | PAC | U.S. government obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	6	24
Other Postretirement | PAC | U.S. government obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | U.S. government obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Corporate obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	49	79
Other Postretirement | PAC | Corporate obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Corporate obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	49	79
Other Postretirement | PAC | Corporate obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Municipal obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	13	15
Other Postretirement | PAC | Municipal obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Municipal obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	13	15
Other Postretirement | PAC | Municipal obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Agency, asset and mortgage-backed obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	47	35
Other Postretirement | PAC | Agency, asset and mortgage-backed obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Agency, asset and mortgage-backed obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	47	35
Other Postretirement | PAC | Agency, asset and mortgage-backed obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Equity securities, U.S. companies | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	7	4
Other Postretirement | PAC | Equity securities, U.S. companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	7	4
Other Postretirement | PAC | Equity securities, U.S. companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
Other Postretirement | PAC | Equity securities, U.S. companies | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 0	$ 0
Other Postretirement | PAC | Investment funds
Defined Benefit Plan Disclosure [Line Items]
Percentage of funds comprised of equity securities	41.00%	39.00%
Percentage of funds comprised of debt securities	59.00%	61.00%
Percentage of funds invested in United States securities	91.00%	90.00%
Percentage of funds invested in international securities	9.00%	10.00%
Other Postretirement | PAC | Investment funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 132	$ 161
Other Postretirement | PAC | Limited partnership interests | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	1
U.S. | Pension
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	2,013	2,795	2,824
U.S. | Pension | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	1,096	1,412
U.S. | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	308	277
U.S. | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	788	1,135
U.S. | Pension | Cash equivalents | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	51	64
U.S. | Pension | Cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | Cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	51	64
U.S. | Pension | U.S. government obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	109	142
U.S. | Pension | U.S. government obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	109	142
U.S. | Pension | U.S. government obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | Corporate obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	613	912
U.S. | Pension | Corporate obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | Corporate obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	613	912
U.S. | Pension | Municipal obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	43	66
U.S. | Pension | Municipal obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | Municipal obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	43	66
U.S. | Pension | Agency, asset and mortgage-backed obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	81	93
U.S. | Pension | Agency, asset and mortgage-backed obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | Agency, asset and mortgage-backed obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	81	93
U.S. | Pension | Equity securities, U.S. companies | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	198	135
U.S. | Pension | Equity securities, U.S. companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	198	135
U.S. | Pension | Equity securities, U.S. companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 0	$ 0
U.S. | Pension | Investment funds
Defined Benefit Plan Disclosure [Line Items]
Percentage of funds comprised of equity securities	53.00%	54.00%
Percentage of funds comprised of debt securities	47.00%	46.00%
Percentage of funds invested in United States securities	95.00%	89.00%
Percentage of funds invested in international securities	5.00%	11.00%
U.S. | Pension | Investment funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 885	$ 1,349
U.S. | Pension | Limited partnership interests | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	32	34
U.S. | Pension | PAC
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	758	1,058	$ 1,064
U.S. | Pension | PAC | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	380	486
U.S. | Pension | PAC | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	110	112
U.S. | Pension | PAC | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	270	374
U.S. | Pension | PAC | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Cash equivalents | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	10	15
U.S. | Pension | PAC | Cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Cash equivalents | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	10	15
U.S. | Pension | PAC | Cash equivalents | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | U.S. government obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	41	51
U.S. | Pension | PAC | U.S. government obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	41	51
U.S. | Pension | PAC | U.S. government obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | U.S. government obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Corporate obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	211	299
U.S. | Pension | PAC | Corporate obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Corporate obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	211	299
U.S. | Pension | PAC | Corporate obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Municipal obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	15	22
U.S. | Pension | PAC | Municipal obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Municipal obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	15	22
U.S. | Pension | PAC | Municipal obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Agency, asset and mortgage-backed obligations | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	34	38
U.S. | Pension | PAC | Agency, asset and mortgage-backed obligations | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Agency, asset and mortgage-backed obligations | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	34	38
U.S. | Pension | PAC | Agency, asset and mortgage-backed obligations | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Equity securities, U.S. companies | Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	69	61
U.S. | Pension | PAC | Equity securities, U.S. companies | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	69	61
U.S. | Pension | PAC | Equity securities, U.S. companies | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	0	0
U.S. | Pension | PAC | Equity securities, U.S. companies | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 0	$ 0
U.S. | Pension | PAC | Investment funds
Defined Benefit Plan Disclosure [Line Items]
Percentage of funds comprised of equity securities	50.00%	59.00%
Percentage of funds comprised of debt securities	50.00%	41.00%
Percentage of funds invested in United States securities	90.00%	84.00%
Percentage of funds invested in international securities	10.00%	16.00%
U.S. | Pension | PAC | Investment funds | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 346	$ 538
U.S. | Pension | PAC | Limited partnership interests | NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value, end of year	$ 32	$ 34