Statement of Net Income (Unaudited) - NWP - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenues [Abstract]
Revenues	$ 2,781	$ 2,336	$ 5,829	$ 5,107
Costs and Expenses [Abstract]
Depreciation, depletion, and amortization	605	540	1,190	1,088
Other Operating Income (Expense), Net	13	(27)	3	(44)
Total costs and expenses	1,836	1,640	3,790	3,399
Operating income (loss)	945	696	2,039	1,708
Interest expense	(350)	(339)	(699)	(688)
Other Nonoperating Income (Expense)	16	33	30	64
Net income	546	401	1,237	1,033
Northwest Pipeline LLC [Member]
Revenues [Abstract]
Revenues	113	105	224	222
Costs and Expenses [Abstract]
Utilities Operating Expense, Maintenance and Operations	24	23	45	45
General and Administrative Expense	11	12	24	24
Depreciation, depletion, and amortization	30	27	59	54
Taxes, Miscellaneous	4	4	8	7
Other Operating Income (Expense), Net	(4)	(6)	(10)	(9)
Total costs and expenses	65	60	126	121
Operating income (loss)	48	45	98	101
Interest expense	(7)	(7)	(14)	(14)
Public Utilities, Allowance for Funds Used During Construction, Additions	2	2	4	4
Other Nonoperating Income (Expense)	2	3	3	5
Net income	45	43	91	96
Natural Gas, US Regulated | Northwest Pipeline LLC [Member]
Revenues [Abstract]
Revenues	107	99	212	209
Natural Gas, Storage | Northwest Pipeline LLC [Member]
Revenues [Abstract]
Revenues	4	4	8	8
Product and Service, Other | Northwest Pipeline LLC [Member]
Revenues [Abstract]
Revenues	$ 2	$ 2	$ 4	$ 5