Short-term Debt and Credit Facilities - PAC (Details)	Jan. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Credit facilities		$ 10,873,000,000	$ 11,281,000,000
Tax-exempt bond support and letters of credit		(620,000,000)	(589,000,000)
Net credit facilities		9,134,000,000	8,683,000,000
PAC
Line of Credit Facility [Line Items]
Credit facilities		1,200,000,000	1,200,000,000
Tax-exempt bond support and letters of credit		(249,000,000)	(218,000,000)
Net credit facilities		951,000,000	982,000,000
Letters of credit outstanding		38,000,000	$ 19,000,000
PAC | Unsecured credit facility, $1.2 billion, expiring June 2025 | Line of credit
Line of Credit Facility [Line Items]
Credit facilities		$ 1,200,000,000
Debt to capitalization ratio		0.65
PAC | Unsecured credit facility, $800 million, expiring January 2024 | Line of credit | Subsequent event
Line of Credit Facility [Line Items]
Credit facilities	$ 800,000,000
Line of credit, amount drawn	$ 0