Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment
Regulated Energy	$ 2,737,100	$ 2,661,800
Unregulated Energy	472,100	463,700
Other Businesses and Eliminations	38,200	29,900
Total property, plant and equipment	3,247,400	3,155,400
Less: Accumulated depreciation and amortization	(585,800)	(567,600)
Property, Plant and Equipment, Net	2,828,200	2,735,900
Current Assets
Cash and cash equivalents	700	7,900
Trade and other receivables	97,000	76,700
Accounts Receivable, Allowance for Credit Loss, Current	(4,158)	(3,291)
Accounts Receivable, before Allowance for Credit Loss, Current	101,200	80,000
Accrued revenue	31,400	37,800
Propane inventory, at average cost	9,100	8,900
Other inventory, at average cost	19,000	18,000
Regulatory assets	17,300	23,900
Storage gas prepayments	900	3,800
Income taxes receivable	4,900	6,800
Prepaid expenses	15,500	17,300
Derivative assets, at fair value	600	600
Other current assets	3,200	2,600
Total current assets	199,600	204,300
Deferred Charges and Other Assets
Goodwill	507,700	507,700
Other intangible assets, net	14,600	15,000
Investments, at fair value	14,400	14,400
Operating Lease, Right-of-Use Asset	9,700	10,500
Regulatory assets	77,300	77,400
Receivables and other deferred charges	13,000	11,700
Total deferred charges and other assets	636,800	636,800
Total Assets	3,664,600	3,577,000
Stockholders’ equity
Preferred stock, par value $0.01 per share (authorized 2,000,000 shares), no shares issued and outstanding	0	0
Common stock, par value $0.4867 per share (authorized 50,000,000 shares)	11,200	11,100
Additional paid-in capital	852,000	830,500
Retained earnings	586,400	550,300
Accumulated other comprehensive loss	(2,300)	(1,700)
Deferred compensation obligation	12,200	9,800
Treasury stock	(12,200)	(9,800)
Total stockholders’ equity	1,447,300	1,390,200
Total capitalization	2,707,300	2,651,900
Current Liabilities
Less: current maturities	25,500	25,500
Short-term borrowing	215,400	196,500
Accounts payable	76,600	78,300
Customer deposits and refunds	42,000	45,700
Accrued interest	16,200	4,800
Dividends payable	14,700	14,700
Accrued compensation	9,500	23,900
Regulatory liabilities	16,400	16,100
Derivative liabilities, at fair value	100	0
Other accrued liabilities	17,300	13,900
Total current liabilities	433,700	419,400
Deferred Credits and Other Liabilities
Deferred income taxes	312,300	296,100
Regulatory liabilities	185,300	184,000
Environmental liabilities	2,300	2,200
Other pension and benefit costs	13,000	13,200
Operating Lease, Liability, Noncurrent	8,400	8,700
Deferred investment tax credits and other liabilities	1,400	1,400
Total deferred credits and other liabilities	523,600	505,700
Total Capitalization and Liabilities	3,664,600	3,577,000
Other Businesses and Eliminations	38,200	29,900
Property, Plant and Equipment, Gross	3,247,400	3,155,400
Construction Work in Progress	166,600	148,100
Property, Plant and Equipment, Net	2,828,200	2,735,900
Trade and other receivables	97,000	76,700
Income taxes receivable	4,900	6,800
Other current assets	3,200	2,600
Assets, Current	199,600	204,300
Receivables and other deferred charges	13,000	11,700
Deferred Charges And Other Assets	636,800	636,800
Total identifiable assets	3,664,600	3,577,000
Regulated Energy	2,737,100	2,661,800
Unregulated Energy	472,100	463,700
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	585,800	567,600
Cash and cash equivalents	700	7,900
Accounts Receivable, before Allowance for Credit Loss, Current	101,200	80,000
Allowance for uncollectible accounts	4,158	3,291
Accrued revenue	31,400	37,800
Propane inventory, at average cost	9,100	8,900
Other inventory, at average cost	19,000	18,000
Regulatory assets	17,300	23,900
Storage gas prepayments	900	3,800
Prepaid expenses	15,500	17,300
Derivative assets, at fair value	600	600
Goodwill	507,700	507,700
Other intangible assets, net	14,600	15,000
Investments, at fair value	14,400	14,400
Operating Lease, Right-of-Use Asset	9,700	10,500
Regulatory assets	77,300	77,400
Preferred stock, par value $0.01 per share (authorized 2,000,000 shares), no shares issued and outstanding	0	0
Stockholders' Equity Attributable to Parent	1,447,300	1,390,200
Capitalization, Long-term Debt and Equity	2,707,300	2,651,900
Accounts payable	76,600	78,300
Other accrued liabilities	17,300	13,900
Liabilities, Current	433,700	419,400
Regulatory liabilities	185,300	184,000
Operating Lease, Liability, Noncurrent	8,400	8,700
Deferred investment tax credits and other liabilities	1,400	1,400
Deferred Credits and Other Liabilities	523,600	505,700
Liabilities and Equity	3,664,600	3,577,000
Common stock, par value $0.4867 per share (authorized 50,000,000 shares)	11,200	11,100
Additional paid-in capital	852,000	830,500
Retained earnings	586,400	550,300
Accumulated other comprehensive loss	(2,300)	(1,700)
Deferred compensation obligation	12,200	9,800
Treasury Stock, Value	12,200	9,800
Long-term Debt and Capital Lease Obligations, Net of Current Maturities	1,260,000	1,261,700
Less: current maturities	25,500	25,500
Short-term borrowing	215,400	196,500
Customer deposits and refunds	42,000	45,700
Accrued interest	16,200	4,800
Dividends payable	14,700	14,700
Accrued compensation	9,500	23,900
Regulatory liabilities	16,400	16,100
Energy Marketing Contract Liabilities, Current	100	0
Deferred income taxes	312,300	296,100
Environmental liabilities	2,300	2,200
Other pension and benefit costs	13,000	13,200
Energy Marketing Contracts Assets, Noncurrent	100	100
Energy Marketing Contract Liabilities, Noncurrent	900	$ 100
Accrued compensation	$ (14,600)