Balance Sheet Components - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	$ 105	$ 137
Regulatory Assets, Non-Current	817	847
Regulatory Liabilities, Current	102	108
Regulatory Liabilities, Non-Current	843	834
Other Income Tax Related Liabilities [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	6	5
Regulatory Liabilities, Non-Current	56	59
Excess Deferred Income Taxes [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	14	14
Regulatory Liabilities, Non-Current	276	279
Deferred Climate Commitment Act Revenues [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	29	44
Regulatory Liabilities, Non-Current	0	0
Deferred Power Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	8	8
Regulatory Liabilities, Non-Current	5	6
Deferred Natural Gas Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	32	25
Regulatory Liabilities, Non-Current	0	0
Decoupling Rebate [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	1	4
Regulatory Liabilities, Non-Current	8	0
Utility Plant Retirement Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	0	0
Regulatory Liabilities, Non-Current	456	448
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	0	0
Regulatory Liabilities, Non-Current	24	24
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	0	0
Regulatory Liabilities, Non-Current	8	10
Other Regulatory Liabilities [Member]
Regulated Asset Liability [Line Items]
Regulatory Liabilities, Current	12	8
Regulatory Liabilities, Non-Current	10	8
Energy Commodity Derivatives [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	27
Regulatory Assets, Non-Current	12	14
Deferred Climate Commitment Act Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	24	50
Regulatory Assets, Non-Current	0	0
Deferred Power Costs [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	29	9
Regulatory Assets, Non-Current	9	27
Decoupling Surcharge [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	13	12
Regulatory Assets, Non-Current	8	12
Income Tax Related Assets [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	244	246
Pension and Other Postretirement Benefit Plans [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	105	106
Interest Rate Swaps [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	171	172
AFUDC Above FERC Allowed Rate [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	49	49
Settlement with Coeur d'Alene Tribe [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	35	36
Advanced Meter Infrastructure [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	26	26
Utility Plant Abandoned [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	4	4
Regulatory Assets, Non-Current	38	38
COVID-19 Deferrals [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	10	12
Demand Side Management Programs [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	0	0
Regulatory Assets, Non-Current	37	38
Other Regulatory Assets [Member]
Regulated Asset Liability [Line Items]
Regulatory Assets, Current	35	35
Regulatory Assets, Non-Current	$ 73	$ 71