Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Comprehensive income (loss):
Net income (loss)	$ 200	$ 125	$ 739	$ 887
Cash flow hedging activities:
Net unrealized gain (loss) from derivative instruments, net of taxes of $3 and $6 in 2018, and $2 and $1 in 2017	(5)	(9)	(19)	(5)
Reclassifications into earnings of net derivative instruments (gain) loss, net of taxes of ($2) and ($3) in 2018, and $1 and $1 in 2017	7	2	10	0
Pension and other postretirement benefits:
Amortization of prior service cost (credit) included in net periodic benefit cost (credit), net of taxes of $1 and $2 in 2017	0	0	0	(2)
Net actuarial gain (loss) arising during the year, net of taxes of ($0) and ($1) in 2018	0	0	4	0
Amortization of actuarial (gain) loss and net actuarial loss from settlements included in net periodic benefit cost (credit), net of taxes of ($3) and ($5) in 2018, and ($2) and ($7) in 2017	4	4	14	13
Other comprehensive income (loss)	6	(3)	9	6
Comprehensive income (loss)	206	122	748	893
Less: Comprehensive income (loss) attributable to noncontrolling interests	72	89	321	398
Comprehensive income (loss) attributable to The Williams Companies, Inc.	$ 134	$ 33	$ 427	$ 495