Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Current assets:
Cash and cash equivalents	$ 64,904	$ 54,161	$ 55,094
Receivables, net	948,024	946,741	784,582
Inventories	380,316	335,609	316,737
Current regulatory assets	89,078	118,691	98,452
Prepayments and other current assets	89,586	95,741	68,409
Total current assets	1,571,908	1,550,943	1,323,274
Noncurrent assets:
Property, plant and equipment	8,958,600	8,972,849	8,288,879
Less accumulated depreciation, depletion and amortization	3,158,091	3,216,461	3,096,371
Net property, plant and equipment	5,800,509	5,756,388	5,192,508
Goodwill	763,262	765,386	714,963
Other intangible assets, net	21,389	22,578	23,961
Regulatory assets	359,228	357,851	379,917
Investments	174,555	175,476	167,741
Operating lease right-of-use assets	119,845	124,138	116,663
Other	160,019	157,675	150,248
Total noncurrent assets	7,398,807	7,359,492	6,746,001
Total assets	8,970,715	8,910,435	8,069,275
Current liabilities:
Short-term borrowings	99,958	0	50,000
Long-term debt due within one year	147,953	148,053	1,552
Accounts payable	449,746	478,933	379,348
Taxes payable	90,572	80,372	88,711
Dividends payable	44,229	44,229	42,740
Accrued compensation	64,796	81,904	69,612
Operating lease liabilities due within one year	34,618	35,368	32,562
Regulatory liabilities due within one year	31,186	16,303	34,266
Other accrued liabilities	203,670	207,078	201,246
Total current liabilities	1,166,728	1,092,240	900,037
Noncurrent liabilities:
Long-term debt	2,599,810	2,593,847	2,251,722
Deferred income taxes	587,940	591,962	528,551
Asset retirement obligations	463,080	458,061	445,170
Regulatory liabilities	433,628	428,790	429,060
Operating lease liabilities	85,874	89,253	84,494
Other	272,937	273,408	329,935
Total noncurrent liabilities	4,443,269	4,435,321	4,068,932
Commitments and contingencies
Stockholders' equity:
Common stock	203,889	203,889	201,733
Other paid-in capital	1,451,464	1,461,205	1,382,158
Retained earnings	1,749,726	1,762,410	1,567,551
Accumulated other comprehensive loss	(40,735)	(41,004)	(47,510)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)	(3,626)
Total stockholders' equity	3,360,718	3,382,874	3,100,306
Total liabilities and stockholders' equity	$ 8,970,715	$ 8,910,435	$ 8,069,275
Common Stock, Shares Authorized	500,000,000	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00	$ 1.00
Common Stock, Shares, Issued	203,889,661	203,889,661	201,733,458
Treasury Stock, Common, Shares	538,921	538,921	538,921