Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES:
Net income (loss)	$ 384	$ 660
Adjustments to reconcile to net cash provided (used) by operating activities:
Depreciation and amortization	423	433
Provision (benefit) for deferred income taxes	(1)	(1)
Equity (earnings) losses	(82)	(107)
Distributions from unconsolidated affiliates	140	190
Net (gain) loss on disposition of equity-method investments	0	(269)
Amortization of stock-based awards	0	2
Cash provided (used) by changes in current assets and liabilities:
Accounts and notes receivable	258	22
Inventories	(40)	(30)
Other current assets and deferred charges	(12)	19
Accounts payable	(197)	38
Accrued liabilities	(58)	(28)
Affiliate accounts receivable and payable – net	(76)	(32)
Other, including changes in noncurrent assets and liabilities	13	(45)
Net cash provided (used) by operating activities	752	852
FINANCING ACTIVITIES:
Proceeds from (payments of) commercial paper – net	0	(93)
Proceeds from long-term debt	1,808	0
Payments of long-term debt	(750)	(1,350)
Proceeds from sales of common units	0	2,178
Distributions paid	(552)	(796)
Distributions to noncontrolling interests	(35)	(43)
Contributions from noncontrolling interests	3	4
Contributions from (distributions to) The Williams Companies, Inc. – net	2	(11)
Payments for debt issuance costs	(18)	0
Other – net	(34)	(23)
Net cash provided (used) by financing activities	424	(134)
INVESTING ACTIVITIES:
Capital expenditures (1)	(948)	(509)
Dispositions – net	(1)	(2)
Contributions in aid of construction	190	131
Proceeds from dispositions of equity-method investments	0	200
Purchases of and contributions to equity-method investments	(21)	(52)
Other – net	(9)	(6)
Net cash provided (used) by investing activities	(789)	(238)
Increase (decrease) in cash and cash equivalents	387	480
Cash and cash equivalents at beginning of year	881	145
Cash and cash equivalents at end of period	1,268	625
(1) Increases to property, plant, and equipment	(925)	(569)
Changes in related accounts payable and accrued liabilities	(23)	60
Capital expenditures	$ (948)	$ (509)