Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets
Property, plant and equipment, at cost	$ 13,468,046	$ 12,610,376
Less: accumulated depreciation	2,592,368	2,358,510
Net property, plant and equipment	10,875,678	10,251,866
Current assets:
Cash and cash equivalents	23,366	10,567
Accounts receivable, net	119,803	141,025
Unbilled revenues	82,643	119,896
Inventory - materials and supplies	41,565	33,756
Inventory - gas stored	188,147	75,804
Prepayments and other current assets	39,241	36,597
Regulatory assets	46,541	20,150
Total current assets	541,306	437,795
Regulatory assets	1,300,554	1,429,840
Deferred charges and other assets, net	172,236	141,955
Funds restricted for construction activity	1,336	1,313
Goodwill	2,340,792	2,340,815
Operating lease right-of-use assets	43,095	48,930
Intangible assets	4,795	5,764
Total assets	15,279,792	14,658,278
Stockholders' equity:
Common stock at $0.50 par value, authorized 600,000,000 shares, issued 265,530,007 and 256,102,388 as of September 30, 2022 and December 31, 2021	132,764	128,050
Capital in excess of par value	3,723,523	3,705,814
Retained earnings	1,570,652	1,434,201
Treasury stock, at cost, 3,239,286 and 3,234,765 shares as of September 30, 2022 and December 31, 2021	(83,837)	(83,615)
Total stockholders' equity	5,343,102	5,184,450
Long-term debt, excluding current portion	6,220,973	5,815,211
Less: debt issuance costs	47,345	35,707
Long-term debt, excluding current portion, net of debt issuance costs	6,173,628	5,779,504
Commitments and contingencies (See Note 13)
Current liabilities:
Current portion of long-term debt	149,926	132,146
Loans payable	213,235	65,000
Accounts payable	217,597	192,932
Book overdraft	17,396	81,722
Accrued interest	75,305	40,815
Accrued taxes	33,316	37,924
Regulatory liabilities	1,196	384
Other accrued liabilities	140,122	124,140
Total current liabilities	848,093	675,063
Deferred credits and other liabilities:
Deferred income taxes and investment tax credits	1,304,548	1,406,537
Customers' advances for construction	121,247	103,619
Regulatory liabilities	771,734	769,617
Asset retirement obligations	1,274	1,256
Operating lease liabilities	39,657	48,230
Pension and other postretirement benefit liabilities	54,309	50,226
Other	25,929	43,666
Total deferred credits and other liabilities	2,318,698	2,423,151
Contributions in aid of construction	596,271	596,110
Total liabilities and equity	$ 15,279,792	$ 14,658,278