CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net income	$ 895,902	$ 775,460
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	982,682	841,360
Conservation and demand side management program amortization	3,089	4,063
Nuclear fuel amortization	89,475	82,627
Deferred income taxes	479,100	429,091
Amortization of investment tax credits	(3,920)	(4,151)
Allowance for equity funds used during construction	(45,042)	(40,728)
Equity earnings of unconsolidated subsidiaries	(32,500)	(24,360)
Dividends from unconsolidated subsidiaries	34,502	29,434
Share-based compensation expense	29,872	29,765
Loss on Monticello life cycle management/extended power uprate project	0	129,463
Net realized and unrealized hedging and derivative transactions	3,307	18,808
Other	(266)	0
Changes in operating assets and liabilities:
Accounts receivable	(29,585)	85,276
Accrued unbilled revenues	87,015	182,425
Inventories	(6,203)	(47,659)
Other current assets	80,566	72,445
Accounts payable	50,526	(116,137)
Net regulatory assets and liabilities	3,911	116,068
Other current liabilities	(76,011)	60,293
Pension and other employee benefit obligations	(96,350)	(82,013)
Change in other noncurrent assets	(11,815)	2,374
Change in other noncurrent liabilities	(25,401)	(53,982)
Net cash provided by operating activities	2,412,854	2,489,922
Investing activities
Utility capital/construction expenditures	(2,186,483)	(2,186,369)
Proceeds from insurance recoveries	1,595	27,237
Allowance for equity funds used during construction	45,042	40,728
Purchases of investment securities	(390,031)	(773,260)
Proceeds from the sale of investment securities	327,378	753,924
Investments in WYCO Development LLC and other	(3,962)	(832)
Other, net	204	(676)
Net cash used in investing activities	(2,206,257)	(2,139,248)
Financing activities
Repayments of short-term borrowings, net	(480,000)	(955,500)
Proceeds from issuance of long-term debt	1,632,642	1,627,190
Repayments of long-term debt	(580,167)	(250,644)
Proceeds from issuance of common stock	0	5,298
Purchase of common stock for settlement of equity awards	(2,810)	0
Dividends paid	(507,817)	(452,217)
Net cash provided by (used in) financing activities	61,848	(25,873)
Net change in cash and cash equivalents	268,445	324,801
Cash and cash equivalents at beginning of period	84,940	79,608
Cash and cash equivalents at end of period	353,385	404,409
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(461,302)	(424,878)
Cash received for income taxes, net	61,245	57,632
Supplemental disclosure of non-cash investing and financing transactions:
Property, plant and equipment additions in accounts payable	221,155	284,864
Issuance of common stock for reinvested dividends and equity awards	$ 17,527	$ 39,169