Earnings (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share Table [Line Items]
Net income (loss) attributable to The Williams Companies, Inc. available to common stockholders for basic and diluted earnings (loss) per common share	$ 33	$ 61	$ 487	$ (409)
Basic weighted-average shares	826,779	750,754	825,925	750,579
Effect of dilutive securities:
Diluted weighted-average shares	829,368	751,858	828,150	750,579
Earnings (loss) per common share:
Basic	$ 0.04	$ 0.08	$ 0.59	$ (0.55)
Diluted	$ 0.04	$ 0.08	$ 0.59	$ (0.55)
Nonvested restricted stock units [Member]
Effect of dilutive securities:
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	1,889	568	1,567	0
Stock Options [Member]
Effect of dilutive securities:
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	700	536	658	0