Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Capital in Excess of Par Value	Retained Deficit	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Stockholders' Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2015	$ 16,225	$ 0	$ 784	$ 14,807	$ (7,960)	$ (442)	$ (1,041)	$ 6,148	$ 10,077
Net income (loss)	(350)	0	0	0	(424)	0	0	(424)	74
Other comprehensive income (loss)	172	0	0	0	0	103	0	103	69
Cash dividends – common stock	(1,261)	0	0	0	(1,261)	0	0	(1,261)	0
Dividends and distributions to noncontrolling interests	(940)	0	0	0	0	0	0	0	(940)
Stock-based compensation and related common stock issuances, net of tax	57	0	1	56	0	0	0	57	0
Sales of limited partner units of Williams Partners L.P.	114	0	0	0	0	0	0	0	114
Changes in ownership of consolidated subsidiaries, net	(6)	0	0	12	0	0	0	12	(18)
Contributions from noncontrolling interests	29	0	0	0	0	0	0	0	29
Other	6	0	0	12	(4)	0	0	8	(2)
Net increase (decrease) in equity	(2,179)	0	1	80	(1,689)	103	0	(1,505)	(674)
Ending balance at Dec. 31, 2016	14,046	0	785	14,887	(9,649)	(339)	(1,041)	4,643	9,403
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	37	0	0	1	36	0	0	37	0
Net income (loss)	2,509	0	0	0	2,174	0	0	2,174	335
Other comprehensive income (loss)	100	0	0	0	0	101	0	101	(1)
Stock Issued During Period, Value, New Issues	2,118	0	75	2,043	0	0	0	2,118	0
Cash dividends – common stock	(992)	0	0	0	(992)	0	0	(992)	0
Dividends and distributions to noncontrolling interests	(883)	0	0	0	0	0	0	0	(883)
Stock-based compensation and related common stock issuances, net of tax	74	0	1	73	0	0	0	74	0
Sales of limited partner units of Williams Partners L.P.	61	0	0	0	0	0	0	0	61
Changes in ownership of consolidated subsidiaries, net	(910)	0	0	1,497	0	0	0	1,497	(2,407)
Contributions from noncontrolling interests	17	0	0	0	0	0	0	0	17
Other	(2)	0	0	7	(3)	0	0	4	(6)
Net increase (decrease) in equity	2,129	0	76	3,621	1,215	101	0	5,013	(2,884)
Ending balance at Dec. 31, 2017	16,175	0	861	18,508	(8,434)	(238)	(1,041)	9,656	6,519
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	(121)	0	0	0	(23)	(61)	0	(84)	(37)
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)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	1,862	0	382	6,112	0	(3)	0	6,491	(4,629)
Stock Issued During Period, Value, New Issues	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
Noncontrolling Interest, Decrease from Deconsolidation	(267)	0	0	0	0	0	0	0	(267)
Other	(5)	0	1	(1)	(4)	0	0	(4)	(1)
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