Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings (Deficit)	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Stockholders' Equity	Noncontrolling Interests
Beginning balance at Dec. 31, 2012	$ 7,427	$ 716	$ 11,134	$ (5,695)	$ (362)	$ (1,041)	$ 4,752	$ 2,675
Net income (loss)	668	0	0	430	0	0	430	238
Other comprehensive income (loss)	198	0	0	0	198	0	198	0
Cash dividends - common stock (Note 15)	(982)	0	0	(982)	0	0	(982)	0
Dividends and distributions to noncontrolling interests	(489)	0	0	0	0	0	0	(489)
Issuance of common stock from debentures conversion	1	0	1	0	0	0	1	0
Stock-based compensation and related common stock issuances, net of tax	56	2	54	0	0	0	56	0
Sales of limited partner units of Williams Partners L.P.	1,819	0	0	0	0	0	0	1,819
Changes in ownership of consolidated subsidiaries, net	(243)	0	409	0	0	0	409	(652)
Contributions from noncontrolling interests	467	0	0	0	0	0	0	467
Other	(1)	0	1	(1)	0	0	0	(1)
Net increase (decrease) in equity	1,494	2	465	(553)	198	0	112	1,382
Ending balance at Dec. 31, 2013	8,921	718	11,599	(6,248)	(164)	(1,041)	4,864	4,057
Net income (loss)	2,339	0	0	2,114	0	0	2,114	225
Other comprehensive income (loss)	(176)	0	0	0	(157)	0	(157)	(19)
Noncontrolling interest resulting from acquisition of business (Note 2)	7,502	0	0	0	0	0	0	7,502
Cash dividends - common stock (Note 15)	(1,412)	0	0	(1,412)	0	0	(1,412)	0
Dividends and distributions to noncontrolling interests	(840)	0	0	0	0	0	0	(840)
Stock-based compensation and related common stock issuances, net of tax	88	3	85	0	0	0	88	0
Sales of limited partner units of Williams Partners L.P.	55	0	0	0	0	0	0	55
Changes in ownership of consolidated subsidiaries, net	44	0	(73)	0	(20)	0	(93)	137
Issuance of common stock for acquisition of business (Note 15)	3,378	61	3,317	0	0	0	3,378	0
Contributions from noncontrolling interests	340	0	0	0	0	0	0	340
Deconsolidation of Bluegrass Pipeline (Note 5)	(63)	0	0	0	0	0	0	(63)
Other	(4)	0	(3)	(2)	0	0	(5)	1
Net increase (decrease) in equity	11,251	64	3,326	700	(177)	0	3,913	7,338
Ending balance at Dec. 31, 2014	20,172	782	14,925	(5,548)	(341)	(1,041)	8,777	11,395
Net income (loss)	(1,314)	0	0	(571)	0	0	(571)	(743)
Other comprehensive income (loss)	(171)	0	0	0	(101)	0	(101)	(70)
Cash dividends - common stock (Note 15)	(1,836)	0	0	(1,836)	0	0	(1,836)	0
Dividends and distributions to noncontrolling interests	(942)	0	0	0	0	0	0	(942)
Stock-based compensation and related common stock issuances, net of tax	30	2	28	0	0	0	30	0
Sales of limited partner units of Williams Partners L.P.	59	0	0	0	0	0	0	59
Changes in ownership of consolidated subsidiaries, net	94	0	(160)	0	0	0	(160)	254
Contributions from noncontrolling interests	111	0	0	0	0	0	0	111
Other	22	0	14	(5)	0	0	9	13
Net increase (decrease) in equity	(3,947)	2	(118)	(2,412)	(101)	0	(2,629)	(1,318)
Ending balance at Dec. 31, 2015	$ 16,225	$ 784	$ 14,807	$ (7,960)	$ (442)	$ (1,041)	$ 6,148	$ 10,077