CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Net income	$ 96,457	$ 70,753
Non-cash items included in net income:
Depreciation and amortization	169,239	169,851
Deferred income tax provision and investment tax credits	18,645	(2,200)
Power and natural gas cost amortizations (deferrals), net	(40,178)	6,470
Amortization of debt expense	2,068	2,329
Stock-based compensation expense	3,173	3,705
Equity-related AFUDC	(5,280)	(5,030)
Pension and other postretirement benefit expense	21,925	25,010
Other regulatory assets and liabilities and deferred debits and credits	2,597	12,456
Change in decoupling regulatory deferral	12,602	3,340
Gain on sale of investments	(1,816)	(3,914)
Other	(12,697)	12,807
Contributions to defined benefit pension plan	(42,000)	(22,000)
Cash paid for settlement of interest rate swap agreements	(17,568)	(33,499)
Cash received for settlement of interest rate swap agreements	324
Changes in certain current assets and liabilities:
Accounts and notes receivable	24,521	45,552
Materials and supplies, fuel stock and stored natural gas	(19,753)	(2,444)
Collateral posted for derivative instruments	(9,944)	10,105
Income taxes receivable	10,663	3,549
Other current assets	7,902	6,352
Accounts payable	(889)	(23,328)
Other current liabilities	8,925	15,604
Net cash provided by operating activities	228,916	282,528
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(322,808)	(297,834)
Issuance of notes receivable	(1,791)	(4,343)
Equity and property investments	(12,621)	(3,994)
Proceeds from sale of investments	8,306	6,644
Other	1,984	(1,478)
Net cash used in investing activities	(326,930)	(301,005)
Financing Activities:
Net increase (decrease) in short-term borrowings	66,000	(35,800)
Proceeds from issuance of long-term debt	70,000	165,000
Maturity of long-term debt and finance leases	(2,223)	(2,129)
Issuance of common stock, net of issuance costs	61,345	53,356
Cash dividends paid	(88,204)	(82,281)
Other	(3,876)	(4,818)
Net cash provided by financing activities	103,042	93,328
Net increase in cash and cash equivalents	5,028	74,851
Cash and cash equivalents at beginning of period	14,196	9,896
Cash and cash equivalents at end of period	$ 19,224	$ 84,747