CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Net Income (loss)	$ (31)	$ 278,295
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	188,717	164,576
Conservation amortization	38,219	30,141
Deferred income taxes and tax credits, net	(70,916)	(3,641)
Net unrealized (gain) loss on derivative instruments	192,123	(131,921)
AFUDC - equity	(7,594)	(6,971)
Other non-cash	12,098	2,326
Regulatory assets and liabilities	38,162	4,470
Purchased gas adjustment	123,594	13,915
Other long term assets and liabilities	(17,377)	(7,891)
Change in certain current assets and liabilities:
Accounts receivable and unbilled revenue	61,325	35,847
Materials and supplies	(4,573)	(7,077)
Fuel and natural gas inventory	37,513	12,033
Prepayments and other	(268)	(4,733)
Accounts payable	(270,077)	(57,324)
Taxes payable	83,952	41,726
Other	2,758	18,615
Net cash provided by (used in) operating activities	407,625	382,386
Investing activities:
Construction expenditures - excluding equity AFUDC	(229,040)	(233,131)
Other	9,113	(532)
Net cash provided by (used in) investing activities	(219,927)	(233,663)
Financing activities:
Change in short-term debt, net	(203,600)	(70,250)
Dividends paid	(28,133)	(939)
Proceeds from long-term debt and bonds issued	0	448,075
Other	6,553	5,523
Net cash provided by (used in) financing activities	(225,180)	382,409
Net increase (decrease) in cash, cash equivalents, and restricted cash	(37,482)	531,132
Cash, cash equivalents, and restricted cash at beginning of period	168,785	103,150
Cash, cash equivalents, and restricted cash at end of period	131,303	634,282
Supplemental cash flow information:
Cash payments for interest (net of capitalized interest)	65,479	65,238
Non-cash financing and investing activities:
Accounts payable for capital expenditures eliminated from cash flows	71,823	61,133
Subsidiaries [Member]
Operating activities:
Net Income (loss)	27,535	288,081
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	187,043	163,704
Conservation amortization	38,219	30,141
Deferred income taxes and tax credits, net	(76,785)	5,970
Net unrealized (gain) loss on derivative instruments	192,123	(131,921)
AFUDC - equity	(7,594)	(6,971)
Other non-cash	9,472	(328)
Regulatory assets and liabilities	38,162	4,470
Purchased gas adjustment	123,594	13,915
Other long term assets and liabilities	(16,498)	(5,558)
Change in certain current assets and liabilities:
Accounts receivable and unbilled revenue	60,796	38,183
Materials and supplies	(4,573)	(7,077)
Fuel and natural gas inventory	37,350	12,334
Prepayments and other	(130)	(4,733)
Accounts payable	(269,112)	(61,531)
Taxes payable	90,035	47,162
Other	(5,765)	11,300
Net cash provided by (used in) operating activities	423,872	397,141
Investing activities:
Construction expenditures - excluding equity AFUDC	(228,986)	(232,868)
Other	9,113	(532)
Net cash provided by (used in) investing activities	(219,873)	(233,400)
Financing activities:
Change in short-term debt, net	(220,000)	(70,250)
Dividends paid	(28,002)	(13,896)
Other	6,564	5,576
Net cash provided by (used in) financing activities	(241,438)	(78,570)
Net increase (decrease) in cash, cash equivalents, and restricted cash	(37,439)	85,171
Cash, cash equivalents, and restricted cash at beginning of period	165,885	96,247
Cash, cash equivalents, and restricted cash at end of period	128,446	181,418
Supplemental cash flow information:
Cash payments for interest (net of capitalized interest)	53,568	51,357
Non-cash financing and investing activities:
Accounts payable for capital expenditures eliminated from cash flows	$ 71,823	$ 61,133