CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income	$ 291	$ 239
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	387	369
Nuclear fuel amortization	31	31
Deferred income taxes	59	194
Allowance for equity funds used during construction	(23)	(14)
Equity earnings of unconsolidated subsidiaries	(6)	(8)
Dividends from unconsolidated subsidiaries	9	12
Share-based compensation expense	6	18
Other, net	(1)	4
Changes in operating assets and liabilities:
Accounts receivable	(71)	3
Accrued unbilled revenues	159	174
Inventories	118	88
Other current assets	1	(77)
Accounts payable	(42)	(144)
Net regulatory assets and liabilities	147	18
Other current liabilities	(17)	(43)
Pension and other employee benefit obligations	(146)	(149)
Change in other noncurrent assets	2	0
Change in other noncurrent liabilities	(17)	3
Net cash provided by operating activities	887	718
Investing activities
Utility capital/construction expenditures	(883)	(749)
Allowance for equity funds used during construction	23	14
Purchases of investment securities	(185)	(173)
Proceeds from the sale of investment securities	179	168
Investments in unconsolidated subsidiaries and other	(3)	(3)
Other, net	(3)	(5)
Net cash used in investing activities	(872)	(748)
Financing activities
Proceeds from short-term borrowings, net	211	213
Dividends paid	(175)	(173)
Other	(18)	(21)
Net cash provided by financing activities	18	19
Net change in cash and cash equivalents	33	(11)
Cash and cash equivalents at beginning of period	83	85
Cash and cash equivalents at end of period	116	74
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(181)	(174)
Supplemental disclosure of non-cash investing and financing transactions:
Property, plant and equipment additions in accounts payable	241	186
Issuance of common stock for equity awards	$ 20	$ 12