STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 213,300	$ 159,200	$ 152,200
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	210,000	193,900	163,000
Deferred income taxes	22,100	126,500	123,000
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	(19,100)	(9,300)	(10,000)
Amortization of Regulatory Asset	1,700	1,700	0
Provision for bad debts	4,900	5,100	6,100
Net derivative losses	100	100	200
Changes in operating assets and liabilities:
Accounts receivable	19,500	10,400	8,900
Accrued unbilled revenues	(15,300)	10,400	15,600
Inventories	(16,000)	1,900	1,000
Prepayments and other	(500)	(4,300)	(22,700)
Accounts payable	(6,600)	11,800	13,800
Net regulatory assets and liabilities	(38,200)	(38,100)	55,700
Other current liabilities	11,600	3,400	5,200
Pension and other employee benefit obligations	(16,000)	(21,700)	(15,300)
Other	(5,800)	19,900	(8,100)
Net cash provided by operating activities	446,300	470,500	387,800
Investing activities
Utility capital/construction expenditures	(1,020,900)	(550,600)	(502,500)
Proceeds from insurance recoveries	0	0	3,900
Investments in utility money pool arrangement	(285,000)	(142,000)	(75,000)
Receipts from utility money pool arrangement	350,000	77,000	75,000
Other	0	(500)	1,300
Net cash used in investing activities	(955,900)	(616,100)	(499,900)
Financing activities
Proceeds from (repayments of) short-term borrowings, net	42,000	(50,000)	35,000
Proceeds from issuance of long-term debt	295,000	442,300	296,000
Repayment of long-term debt, including reacquisition premiums	0	(271,600)	(200,000)
Borrowings under utility money pool arrangement	595,000	335,000	636,500
Repayments under utility money pool arrangement	(595,000)	(335,000)	(636,500)
Capital contributions from parent	336,800	143,700	66,200
Dividends paid to parent	(131,000)	(108,800)	(85,100)
Net cash provided by financing activities	542,800	155,600	112,100
Net change in cash and cash equivalents	33,200	10,000	0
Cash and cash equivalents at beginning of period	10,800	800	800
Cash and cash equivalents at end of period	44,000	10,800	800
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(71,200)	(76,000)	(78,200)
Cash paid for income taxes, net	10,600	(41,500)	(61,800)
Supplemental disclosure of non-cash investing transactions:
Inventory transfers to plant, property and equipment	0	13,700	22,600
Property, plant and equipment additions in accounts payable	71,500	85,100	49,500
Allowance for Funds Used During Construction, Investing Activities	$ 19,100	$ 9,300	$ 10,000