CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating Activities:
Net income	$ 54,845	$ 71,565
Non-cash items included in net income:
Depreciation and amortization	65,219	62,609
Deferred income tax provision and investment tax credits	(10,155)	(7,202)
Power and natural gas cost deferrals, net	(53,387)	(7,319)
Amortization of debt expense	1,128	540
Stock-based compensation expense	2,221	1,845
Equity-related AFUDC	(1,562)	(1,946)
Pension and other postretirement benefit expense	3,407	5,368
Other regulatory assets and liabilities	(10,717)	5,234
Other deferred debits and credits	19,759	(443)
Change in decoupling regulatory deferral	19,391	16,729
Realized and unrealized loss (gain) on assets and investments	182	(1,932)
Other	(1,157)	(1,610)
Contributions to defined benefit pension plan	(3,333)	(14,000)
Cash paid for settlement of interest rate swap agreements	(409)	(17,035)
Cash received for settlement of interest rate swap agreements	7,869
Changes in certain current assets and liabilities:
Accounts and notes receivable	37,743	7,765
Inventory	5,900	8,331
Collateral posted for derivative instruments	66,371	38,622
Income taxes receivable	2,925	(4,816)
Other current assets	(17,543)	(5,881)
Accounts payable	(87,195)	(21,828)
Other current liabilities	(7,256)	27,254
Net cash provided by operating activities	94,246	161,850
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(100,490)	(95,987)
Issuance of notes receivable	(1,500)	(197)
Equity and property investments	(4,781)	(231)
Other	518	734
Net cash used in investing activities	(106,253)	(95,681)
Financing Activities:
Net decrease in short-term borrowings	(232,000)	(284,000)
Proceeds from issuance of long-term debt	250,000	399,856
Maturity of long-term debt and finance leases	(809)	(771)
Issuance of common stock, net of issuance costs	29,912	37,886
Cash dividends paid	(35,029)	(31,969)
Other	(2,899)	(5,741)
Net cash provided by financing activities	9,175	115,261
Net increase (decrease) in cash and cash equivalents	(2,832)	181,430
Cash and cash equivalents at beginning of period	13,428	22,168
Cash and cash equivalents at end of period	$ 10,596	$ 203,598