STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income	$ 128,198	$ 123,080
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	144,664	123,820
Demand side management program amortization	1,255	1,255
Deferred income taxes	101,388	99,882
Amortization of investment tax credits	(99)	(160)
Allowance for equity funds used during construction	(6,457)	(7,348)
Net derivative losses	47	203
Other Operating Activities, Cash Flow Statement	9	122
Changes in operating assets and liabilities:
Accounts receivable	(25,134)	(22,160)
Accrued unbilled revenues	(13,682)	(18,307)
Inventories	(2,845)	(1,491)
Prepayments and other	19,361	24,172
Accounts payable	7,817	19,690
Net regulatory assets and liabilities	24,856	(18,480)
Other current liabilities	19,748	18,989
Pension and other employee benefit obligations	(21,638)	(15,606)
Change in other noncurrent assets	(1,697)	(537)
Change in other noncurrent liabilities	(18,690)	3,916
Net cash provided by operating activities	357,101	331,040
Investing activities
Utility capital/construction expenditures	(400,957)	(371,994)
Proceeds from Insurance Settlement, Investing Activities	0	987
Allowance for equity funds used during construction	6,457	7,348
Investments in utility money pool arrangement	0	75,000
Repayments from utility money pool arrangement	0	75,000
Payments for (Proceeds from) Other Investing Activities	493	1,174
Net cash used in investing activities	(394,993)	(364,833)
Financing activities
Proceeds from short-term borrowings, net	(50,000)	(15,000)
Proceeds from issuance of long-term debt, net	442,651	296,152
Borrowings under utility money pool arrangement	323,000	505,000
Repayments under utility money pool arrangement	(323,000)	(505,000)
Capital contributions from parent	45,000	16,225
Repayment of long-term debt, including reacquisition premiums	(271,613)	0
Dividends paid to parent	(82,599)	(57,570)
Net cash provided by financing activities	83,439	239,807
Net change in cash and cash equivalents	45,547	206,014
Cash and cash equivalents at beginning of period	844	834
Cash and cash equivalents at end of period	46,391	206,848
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(58,581)	(47,787)
Cash received for income taxes, net	37,899	49,402
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 40,861	$ 25,445