Statement of Cash Flows - NWP - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	$ 2,346	$ 3,303	$ 2,117
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	2,219	2,071	2,009
Increase (Decrease) in Operating Capital [Abstract]
Increase (Decrease) in Inventories	(9)	13	(110)
Increase (Decrease) in Other Current Assets	9	60	(33)
Other current liabilities	35	(19)	209
Other Operating Activities, Cash Flow Statement	(245)	(216)	(216)
Net cash provided (used) by operating activities	4,974	5,938	4,889
Net Cash Provided by (Used in) Financing Activities [Abstract]
Net cash provided (used) by financing activities	(2,201)	(49)	(3,042)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Capital expenditures (1)	(2,573)	(2,516)	(2,253)
Net cash provided (used) by investing activities	(4,863)	(3,891)	(3,375)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(2,090)	1,998	(1,528)
Cash and cash equivalents at beginning of year	2,150	152	1,680
Cash and cash equivalents at end of year	60	2,150	152
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Property, Plant and Equipment, Additions	(2,581)	(2,564)	(2,394)
Capital expenditures	(2,573)	(2,516)	(2,253)
Northwest Pipeline LLC [Member]
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income	180	180	137
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	111	111	114
Increase (Decrease) in Allowance for Equity Funds Used During Construction	(8)	(3)	(2)
Increase (Decrease) in Operating Capital [Abstract]
Increase (Decrease) in Accounts Receivable, Related Parties	1	0	(1)
Increase (Decrease) in Accounts and Other Receivables	(1)	0	(1)
Increase (Decrease) in Inventories	(1)	1	0
Increase (Decrease) in Other Current Assets	(2)	1	0
Increase (Decrease) in Accounts Payable, Trade	(3)	4	(1)
Increase (Decrease) in Accounts Payable, Related Parties	(1)	1	(1)
IncreaseDecreaseInOtherRegulatoryLiabilities	1	(126)	145
Other current liabilities	(3)	3	1
Increase (Decrease) in Regulatory Assets Noncurrent	(15)	(29)	0
Increase (Decrease) in Regulatory Liabilities Noncurrent	(27)	(20)	(120)
Other Operating Activities, Cash Flow Statement	7	6	(3)
Net cash provided (used) by operating activities	239	129	268
Net Cash Provided by (Used in) Financing Activities [Abstract]
Cash distributions to parent	(150)	(155)	(138)
Increase Decrease In Advances From Affiliates	26	0	0
Net cash provided (used) by financing activities	(124)	(155)	(138)
Net Cash Provided by (Used in) Investing Activities [Abstract]
Capital expenditures (1)	(266)	(125)	(107)
Contributions in aid of construction	5	6	11
Payments for (Proceeds from) Removal Costs	(12)	(8)	(5)
IncreaseDecreaseInAdvancesToAffiliates	158	153	(29)
Net cash provided (used) by investing activities	(115)	26	(130)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Property, Plant and Equipment, Additions	(266)	(140)	(109)
Increase (Decrease) in Accounts Payable And Accrued Liabilities Related To Capital Expenditures	0	15	2
Capital expenditures	$ (266)	$ (125)	$ (107)

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