Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities:
Net income	$ 115,881	$ 54,956
Non-cash items included in net income:
Depreciation and amortization	49,123	45,823
Provision for deferred income taxes	8,883	(5,049)
Power and natural gas cost amortizations (deferrals), net	(48,084)	72
Amortization of debt expense	669	815
Amortization of investment in exchange power	613	613
Stock-based compensation expense	4,845	1,963
Equity-related AFUDC	(1,485)	(1,392)
Pension and other postretirement benefit expense	9,084	8,170
Other regulatory assets and liabilities and deferred debits and credits	1,016	2,127
Change in decoupling regulatory deferral	4,471	5,703
Other	(1,943)	3,778
Contributions to defined benefit pension plan	(7,300)	(7,300)
Changes in certain current assets and liabilities:
Accounts and notes receivable	(9,787)	15,963
Materials and supplies, fuel stock and natural gas stored	(394)	8,815
Collateral posted for derivative instruments	3,432	18,382
Other current assets	1,705	(473)
Accounts payable	16,697	(21,997)
Income taxes payable	19,360	15,432
Other current liabilities	30,095	38,374
Net cash provided by operating activities	196,881	184,775
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(93,615)	(81,817)
Issuance of notes receivable at subsidiaries	(200)	(1,000)
Repayments of notes receivable at subsidiaries	261	0
Equity and property investments made by subsidiaries	(3,504)	(3,671)
Distributions received from investments	149	0
Other	(755)	(866)
Net cash used in investing activities	(97,664)	(87,354)
Financing Activities:
Net decrease in short-term borrowings	(71,000)	(55,398)
Maturity of long-term debt and capital leases	(665)	(3,037)
Issuance of common stock	190	232
Cash dividends paid	(25,615)	(24,634)
Other	(896)	(4,483)
Net cash used in financing activities	(97,986)	(87,320)
Cash And Cash Equivalents Period Increase (Decrease) Including Cash Held for Sale	1,231	10,101
Net increase in cash and cash equivalents for cash classified within assets held for sale	1,026	0
Net increase in cash and cash equivalents	205	10,101
Cash and cash equivalents at beginning of period	14,656	16,172
Cash and cash equivalents at end of period	$ 14,861	$ 26,273