Long-term Debt - PAC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Par value	$ 55,471
Subsidiary debt, current	2,646	$ 2,740
Subsidiary debt, noncurrent	41,154	36,231
Line of credit, maximum capacity	11,596	10,705
Subsidiary debt
Debt Instrument [Line Items]
Par value	42,270
Subsidiary debt	42,150	38,971
Subsidiary debt, current	996	2,740
Subsidiary debt, noncurrent	41,154	36,231
PAC
Debt Instrument [Line Items]
Subsidiary debt	13,588	10,410
Subsidiary debt, current	302	591
Subsidiary debt, noncurrent	13,286	9,819
Line of credit, maximum capacity	2,900	2,000
Additional debt with regulatory authority to issue	5,000
Eligible property subject to lien of mortgages	39,000
PAC | Subsidiary debt
Debt Instrument [Line Items]
Par value	13,702
Subsidiary debt	$ 13,588	10,410
3.60%, due 2024 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	3.60%
Par value	$ 0
Subsidiary debt	$ 0	425
3.35%, due 2025 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	3.35%
Par value	$ 250
Subsidiary debt	$ 250	250
6.71%, due 2026 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	6.71%
Par value	$ 100
Subsidiary debt	$ 100	99
5.10%, due 2029 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.10%
Par value	$ 500
Subsidiary debt	$ 498	0
3.50%, due 2029 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	3.50%
Par value	$ 400
Subsidiary debt	$ 399	399
2.70%, due 2030 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	2.70%
Par value	$ 400
Subsidiary debt	$ 398	398
5.30%, due 2031 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.30%
Par value	$ 700
Subsidiary debt	$ 696	0
7.70%, due 2031 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	7.70%
Par value	$ 300
Subsidiary debt	$ 299	299
5.45%, due 2034 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.45%
Par value	$ 1,100
Subsidiary debt	$ 1,093	0
5.90%, due 2034 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.90%
Par value	$ 200
Subsidiary debt	$ 199	199
5.25%, due 2035 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.25%
Par value	$ 300
Subsidiary debt	$ 299	299
6.10%, due 2036 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	6.10%
Par value	$ 350
Subsidiary debt	$ 348	348
5.75%, due 2037 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.75%
Par value	$ 600
Subsidiary debt	$ 600	600
6.25%, due 2037 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	6.25%
Par value	$ 600
Subsidiary debt	$ 598	597
6.35%, due 2038 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	6.35%
Par value	$ 300
Subsidiary debt	$ 298	298
6.00%, due 2039 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	6.00%
Par value	$ 650
Subsidiary debt	$ 644	644
4.10%, due 2042 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	4.10%
Par value	$ 300
Subsidiary debt	$ 298	298
4.125%, due 2049 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	4.125%
Par value	$ 600
Subsidiary debt	$ 594	594
4.15%, due 2050 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	4.15%
Par value	$ 600
Subsidiary debt	$ 594	593
3.30%, due 2051 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	3.30%
Par value	$ 600
Subsidiary debt	$ 591	591
2.90%, due 2052 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	2.90%
Par value	$ 1,000
Subsidiary debt	$ 985	985
5.35%, due 2053 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.35%
Par value	$ 1,100
Subsidiary debt	$ 1,088	1,087
5.50%, due 2054 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.50%
Par value	$ 1,200
Subsidiary debt	$ 1,189	1,189
5.80%, due 2055 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Stated rate	5.80%
Par value	$ 1,500
Subsidiary debt	1,478	0
Secured, due 2024 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Par value	0
Subsidiary debt	0	166
Secured, due 2025 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Par value	27
Subsidiary debt	27	27
Unsecured, due 2025 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Par value	25
Subsidiary debt	25	$ 25
Unsecured delayed draw term loan facility, expiring June 2025 | PAC | Subsidiary debt
Debt Instrument [Line Items]
Par value	900
Unsecured credit facility, expiring June 2025 | PAC | Line of credit
Debt Instrument [Line Items]
Line of credit, maximum capacity	$ 900
Debt instrument, term	364 days
Minimum | PAC | Subsidiary debt
Debt Instrument [Line Items]
Variable rate	3.20%	4.60%
Maximum | PAC | Subsidiary debt
Debt Instrument [Line Items]
Variable rate	4.45%	5.60%