Statement of Changes in Member's Equity (Unaudited) - NWP - USD ($) $ in Millions	Total	Northwest Pipeline LLC [Member]	Member's Capital Northwest Pipeline LLC [Member]	Retained Earnings Northwest Pipeline LLC [Member]
Balance at beginning of period at Dec. 31, 2023			$ 1,074	$ 59
Capital contributions from parent		$ 0	0
Net income	$ 632	53		53
Cash distributions to parent		33		(33)
Balance at end of period at Mar. 31, 2024		1,153	1,074	79
Balance at beginning of period at Dec. 31, 2024		1,163	1,074	89
Capital contributions from parent		(85)	85
Net income	$ 691	46		46
Cash distributions to parent		24		(24)
Balance at end of period at Mar. 31, 2025		$ 1,270	$ 1,159	$ 111