CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities:
Net income	$ 71,565	$ 68,017
Non-cash items included in net income:
Depreciation and amortization	62,609	55,348
Deferred income tax provision and investment tax credits	(7,202)	5,966
Power and natural gas cost deferrals, net	(7,319)	(7,811)
Amortization of debt expense	540	823
Stock-based compensation expense	1,845	626
Equity-related AFUDC	(1,946)	(1,754)
Pension and other postretirement benefit expense	5,368	7,556
Other regulatory assets and liabilities and deferred debits and credits	4,791	1,762
Change in decoupling regulatory deferral	16,729	(682)
Realized and unrealized gain on assets and investments	(1,932)	(1,728)
Other	(1,610)	(1,255)
Contributions to defined benefit pension plan	(14,000)	(14,000)
Cash paid for settlement of interest rate swap agreements	(17,035)
Changes in certain current assets and liabilities:
Accounts and notes receivable	7,765	6,728
Materials and supplies, fuel stock and stored natural gas	8,331	4,291
Collateral posted for derivative instruments	38,622	1,497
Income taxes receivable	(4,816)	5,442
Other current assets	(5,881)	(260)
Accounts payable	(21,828)	(2,590)
Other current liabilities	27,254	17,114
Net cash provided by operating activities	161,850	145,090
Investing Activities:
Utility property capital expenditures (excluding equity-related AFUDC)	(95,987)	(97,203)
Equity and property investments	(231)	(2,340)
Proceeds from sale of investments		801
Other	537	2,281
Net cash used in investing activities	(95,681)	(96,461)
Financing Activities:
Net decrease in short-term borrowings	(284,000)	(10,000)
Proceeds from issuance of long-term debt	399,856
Maturity of long-term debt and finance leases	(771)	(759)
Issuance of common stock, net of issuance costs	37,886	65
Cash dividends paid	(31,969)	(29,399)
Other	(5,741)	(1,085)
Net cash provided by (used in) financing activities	115,261	(41,178)
Net increase in cash and cash equivalents	181,430	7,451
Cash and cash equivalents at beginning of period	22,168	14,196
Cash and cash equivalents at end of period	$ 203,598	$ 21,647