Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share Table [Line Items]
Net income attributable to The Williams Companies, Inc. available to common stockholders for basic and diluted earnings per common share	$ 152	$ 373
Basic weighted-average shares	827,509	824,548
Effect of dilutive securities:
Diluted weighted-average shares	830,197	826,476
Earnings per common share:
Basic	$ 0.18	$ 0.45
Diluted	$ 0.18	$ 0.45
Nonvested restricted stock units [Member]
Effect of dilutive securities:
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2,095	1,305
Stock Options [Member]
Effect of dilutive securities:
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	593	623