CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income	$ 398,210	$ 376,825
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	353,653	332,383
Demand side management program amortization	672	1,802
Deferred income taxes	223,121	202,599
Amortization of investment tax credits	(2,102)	(2,104)
Allowance for equity funds used during construction	(19,591)	(13,714)
Net realized and unrealized hedging and derivative transactions	907	(1,801)
Other	(11)	(388)
Changes in operating assets and liabilities:
Accounts receivable	4,431	27,080
Accrued unbilled revenues	74,918	70,498
Inventories	(250)	(11,712)
Prepayments and other	11,717	52,526
Accounts payable	(53,706)	(20,164)
Net regulatory assets and liabilities	(28,594)	(31,152)
Other current liabilities	(40,789)	(59,596)
Pension and other employee benefit obligations	(16,691)	(13,080)
Change in other noncurrent assets	(1,149)	(1,422)
Change in other noncurrent liabilities	(1,916)	(15,433)
Net cash provided by operating activities	902,830	893,147
Investing activities
Utility capital/construction expenditures	(995,680)	(802,051)
Proceeds from insurance recoveries	0	608
Allowance for equity funds used during construction	19,591	13,714
Investments in utility money pool arrangement	(659,000)	(437,000)
Repayments from utility money pool arrangement	609,000	437,000
Other, net	(657)	(1,460)
Net cash used in investing activities	(1,026,746)	(789,189)
Financing activities
Repayments of short-term borrowings, net	(129,000)	(14,000)
Borrowings under utility money pool arrangement	40,000	357,000
Repayments under utility money pool arrangement	(40,000)	(306,000)
Proceeds from issuance of long-term debt	393,795	244,527
Repayments of long-term debt	0	(129,500)
Capital contributions from parent	158,080	1,571
Dividends paid to parent	(245,291)	(253,796)
Other	(110)	0
Net cash provided by (used in) financing activities	177,474	(100,198)
Net change in cash and cash equivalents	53,558	3,760
Cash and cash equivalents at beginning of period	5,926	3,585
Cash and cash equivalents at end of period	59,484	7,345
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(145,461)	(149,786)
Cash (paid) received for income taxes, net	(7,752)	32,388
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 133,933	$ 84,417