Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 1,150	$ 1,040
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	1,292	1,274
Allowance for equity funds	(35)	(130)
Equity income, net of distributions	(9)	(44)
Increase (Decrease) in Regulatory Assets and Liabilities	21	(1)
Deferred income taxes and amortization of investment tax credits	341	291
Other, net	3	(72)
Changes in other operating assets and liabilities, net of effects from acquisitions:
Increase (Decrease) in Accounts Receivable and Other Operating Assets	(73)	(252)
Derivative collateral, net	(13)	23
Pension and other postretirement benefit plans	(25)	(9)
Accrued property, income and other taxes	(244)	557
Accounts payable and other liabilities	20	94
Net cash flows from operating activities	2,428	2,771
Cash flows from investing activities:
Capital expenditures	(1,813)	(2,103)
Acquisitions, net of cash acquired	(588)	(66)
Decrease in restricted cash and investments	30	9
Purchases of available-for-sale securities	(122)	(55)
Proceeds from sales of available-for-sale securities	127	88
Equity method investments	(65)	(282)
Other, net	(6)	(46)
Net cash flows from investing activities	(2,437)	(2,455)
Cash flows from financing activities:
Repayments of Long-term Debt	(950)	(1,000)
Common stock purchases	(19)	0
Proceeds from subsidiary debt	1,163	1,461
Repayments of subsidiary debt	(668)	(1,529)
Net proceeds from short-term debt	617	465
Other, net	(31)	(39)
Net cash flows from financing activities	112	(642)
Effect of exchange rate changes	3	(4)
Net change in cash and cash equivalents	106	(330)
Cash and cash equivalents at beginning of period	721	1,108
Cash and cash equivalents at end of period	$ 827	$ 778