Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Adoption of new accounting standards	Preferred Stock	Preferred Stock Adoption of new accounting standards	Common Stock	Common Stock Adoption of new accounting standards	Capital in Excess of Par Value	Capital in Excess of Par Value Adoption of new accounting standards	Retained Deficit	Retained Deficit Adoption of new accounting standards	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Adoption of new accounting standards	Treasury Stock	Treasury Stock Adoption of new accounting standards	Total Stockholders' Equity	Total Stockholders' Equity Adoption of new accounting standards	Noncontrolling Interests	Noncontrolling Interests Adoption of new accounting standards
Beginning balance at Dec. 31, 2017	$ 16,175		$ 0		$ 861		$ 18,508		$ (8,434)		$ (238)		$ (1,041)		$ 9,656		$ 6,519
Net income (loss)	193		0		0		0		(155)		0		0		(155)		348
Other comprehensive income (loss)	30		0		0		0		0		32		0		32		(2)
WPZ Merger (Note 1)	1,862		0		382		6,112		0		(3)		0		6,491		(4,629)
Issuance of preferred stock (Note 16)	35		35		0		0		0		0		0		35		0
Cash dividends – common stock	(1,386)		0		0		0		(1,386)		0		0		(1,386)		0
Dividends and distributions to noncontrolling interests	(637)		0		0		0		0		0		0		0		(637)
Stock-based compensation and related common stock issuances, net of tax	61		0		1		60		0		0		0		61		0
Sales of limited partner units of Williams Partners L.P.	46		0		0		0		0		0		0		0		46
Changes in ownership of consolidated subsidiaries, net	(4)		0		0		14		0		0		0		14		(18)
Contributions from noncontrolling interests	15		0		0		0		0		0		0		0		15
Deconsolidation of subsidiary (Note 7)	(267)		0		0		0		0		0		0		0		(267)
Other	(5)	$ (121)	0	$ 0	1	$ 0	(1)	$ 0	(4)	$ (23)	0	$ (61)	0	$ 0	(4)	$ (84)	(1)	$ (37)
Net increase (decrease) in equity	(178)		35		384		6,185		(1,568)		(32)		0		5,004		(5,182)
Ending balance at Dec. 31, 2018	15,997		35		1,245		24,693		(10,002)		(270)		(1,041)		14,660		1,337
Net income (loss)	714		0		0		0		850		0		0		850		(136)
Other comprehensive income (loss)	71		0		0		0		0		71		0		71		0
Cash dividends – common stock	(1,842)		0		0		0		(1,842)		0		0		(1,842)		0
Dividends and distributions to noncontrolling interests	(124)		0		0		0		0		0		0		0		(124)
Stock-based compensation and related common stock issuances, net of tax	58		0		2		56		0		0		0		58		0
Sales of limited partner units of Williams Partners L.P.	1,334		0		0		0		0		0		0		0		1,334
Changes in ownership of consolidated subsidiaries, net	141		0		0		(426)		0		0		0		(426)		567
Contributions from noncontrolling interests	36		0		0		0		0		0		0		0		36
Deconsolidation of subsidiary (Note 7)	(13)		0		0		0		0		0		0		0		(13)
Other	(8)		0		0		0		(8)		0		0		(8)		0
Net increase (decrease) in equity	367		0		2		(370)		(1,000)		71		0		(1,297)		1,664
Ending balance at Dec. 31, 2019	16,364		35		1,247		24,323		(11,002)		(199)		(1,041)		13,363		3,001
Net income (loss)	198		0		0		0		211		0		0		211		(13)
Other comprehensive income (loss)	103		0		0		0		0		103		0		103		0
Cash dividends – common stock	(1,941)		0		0		0		(1,941)		0		0		(1,941)		0
Dividends and distributions to noncontrolling interests	(185)		0		0		0		0		0		0		0		(185)
Stock-based compensation and related common stock issuances, net of tax	51		0		1		50		0		0		0		51		0
Contributions from noncontrolling interests	7		0		0		0		0		0		0		0		7
Other	(14)		0		0		(2)		(16)		0		0		(18)		4
Net increase (decrease) in equity	(1,781)		0		1		48		(1,746)		103		0		(1,594)		(187)
Ending balance at Dec. 31, 2020	$ 14,583		$ 35		$ 1,248		$ 24,371		$ (12,748)		$ (96)		$ (1,041)		$ 11,769		$ 2,814