Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 563	$ 495
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	622	626
Allowance for equity funds	(17)	(15)
Equity income, net of distributions	(13)	(16)
Increase (Decrease) in Regulatory Assets and Liabilities	20	60
Deferred income taxes and amortization of investment tax credits	224	72
Other, net	(5)	3
Changes in other operating assets and liabilities, net of effects from acquisitions:
Increase (Decrease) in Accounts Receivable and Other Operating Assets	288	219
Derivative collateral, net	(23)	(3)
Pension and other postretirement benefit plans	(17)	(6)
Accrued property, income and other taxes	(187)	(2)
Accounts payable and other liabilities	(37)	(73)
Net cash flows from operating activities	1,418	1,360
Cash flows from investing activities:
Capital expenditures	(865)	(1,027)
Acquisitions, net of cash acquired	(579)	(13)
Increase in restricted cash and investments	66	41
Purchases of available-for-sale securities	(81)	(34)
Proceeds from sales of available-for-sale securities	83	61
Equity method investments	(65)	(273)
Other, net	(9)	(39)
Net cash flows from investing activities	(1,450)	(1,284)
Cash flows from financing activities:
Repayments of Subordinated Debt	200	500
Common stock purchases	(19)	0
Proceeds from subsidiary debt	844	0
Repayments of subsidiary debt	(425)	(310)
Net proceeds from short-term debt	140	722
Other, net	(12)	(11)
Net cash flows from financing activities	328	(99)
Effect of exchange rate changes	1	1
Net change in cash and cash equivalents	297	(22)
Cash and cash equivalents at beginning of period	721	1,108
Cash and cash equivalents at end of period	$ 1,018	$ 1,086