Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 495	$ 473
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	626	587
Allowance for equity funds	(15)	(31)
Equity income, net of distributions	(16)	(25)
Increase (Decrease) in Regulatory Assets and Liabilities	60	152
Deferred income taxes and amortization of investment tax credits	72	206
Other, net	3	(10)
Changes in other operating assets and liabilities, net of effects from acquisitions:
Increase (Decrease) in Accounts Receivable and Other Operating Assets	219	(18)
Derivative collateral, net	(3)	(21)
Pension and other postretirement benefit plans	(6)	(4)
Accrued property, income and other taxes	(2)	(99)
Accounts payable and other liabilities	(73)	(103)
Net cash flows from operating activities	1,360	1,107
Cash flows from investing activities:
Capital expenditures	(1,027)	(1,426)
Acquisitions, net of cash acquired	(13)	(59)
Decrease in restricted cash and investments	41	12
Purchases of available-for-sale securities	(34)	(68)
Proceeds from sales of available-for-sale securities	61	57
Equity method investments	(273)	(12)
Other, net	(39)	41
Net cash flows from investing activities	(1,284)	(1,455)
Cash flows from financing activities:
Repayments of Subordinated Debt	500	0
Common stock purchases	0	(36)
Proceeds from subsidiary debt	0	484
Repayments of subsidiary debt	(310)	(353)
Net proceeds from short-term debt	722	163
Other, net	(11)	(19)
Net cash flows from financing activities	(99)	239
Effect of exchange rate changes	1	(1)
Net change in cash and cash equivalents	(22)	(110)
Cash and cash equivalents at beginning of period	1,108	617
Cash and cash equivalents at end of period	$ 1,086	$ 507