Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net income	$ 54,956	$ 62,137
Non-cash items included in net income:
Depreciation and amortization	45,823	43,084
Provision for deferred income taxes	(5,049)	17,614
Power and natural gas cost amortizations (deferrals), net	72	3,091
Amortization of debt expense	815	813
Amortization of investment in exchange power	613	613
Stock-based compensation expense	1,963	832
Equity-related AFUDC	(1,392)	(1,650)
Pension and other postretirement benefit expense	8,170	9,348
Other regulatory assets and liabilities and deferred debits and credits	2,127	(6,878)
Change in decoupling regulatory deferral	5,703	14,857
Other	3,778	(116)
Contributions to defined benefit pension plan	(7,300)	(7,400)
Changes in certain current assets and liabilities:
Accounts and notes receivable	15,963	(668)
Materials and supplies, fuel stock and natural gas stored	8,815	6,129
Collateral posted for derivative instruments	18,382	(2,620)
Income taxes receivable	314	14,106
Other current assets	(787)	(116)
Accounts payable	(21,997)	(20,239)
Income taxes payable	15,432	0
Other current liabilities	38,374	16,778
Net cash provided by operating activities	184,775	149,715
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(81,817)	(86,763)
Issuance of notes receivable at subsidiaries	(1,000)	(400)
Equity and property investments made by subsidiaries	(3,671)	(2,627)
Other	(866)	(137)
Net cash used in investing activities	(87,354)	(89,927)
Financing Activities:
Net decrease in short-term borrowings	(55,398)	(15,000)
Maturity of long-term debt and capital leases	(3,037)	(822)
Issuance of common stock	232	315
Cash dividends paid	(24,634)	(23,167)
Other	(4,483)	(3,442)
Net cash used in financing activities	(87,320)	(42,116)
Net increase in cash and cash equivalents	10,101	17,672
Cash and cash equivalents at beginning of period	16,172	8,507
Cash and cash equivalents at end of period	$ 26,273	$ 26,179