Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets
Property, plant and equipment, at cost	$ 14,681,336	$ 13,737,387
Less: accumulated depreciation	2,834,771	2,606,441
Net property, plant and equipment	11,846,565	11,130,946
Current assets:
Cash and cash equivalents	8,505	11,398
Accounts receivable, net	133,735	206,324
Unbilled revenues	75,101	170,504
Inventory - materials and supplies	48,811	46,592
Inventory - gas stored	78,634	153,143
Current assets held for sale	7,461	11,167
Prepayments and other current assets	31,409	39,759
Regulatory assets	25,692	19,272
Total current assets	409,348	658,159
Regulatory assets	1,564,056	1,342,753
Deferred charges and other assets, net	191,958	166,653
Funds restricted for construction activity	1,370	1,342
Goodwill	2,340,661	2,340,792
Non-current assets held for sale	37,327	32,124
Operating lease right-of-use assets	37,836	41,734
Intangible assets	3,672	4,604
Total assets	16,432,793	15,719,107
Stockholders' equity:
Common stock at $0.50 par value, authorized 600,000,000 shares, issued 276,471,716 and 266,973,321 as of September 30, 2023 and December 31, 2022	138,235	133,486
Capital in excess of par value	4,131,834	3,793,262
Retained earnings	1,739,271	1,534,331
Treasury stock, at cost, 3,305,899 and 3,236,237 shares as of September 30, 2023 and December 31, 2022	(86,783)	(83,693)
Total stockholders' equity	5,922,557	5,377,386
Long-term debt, excluding current portion	6,501,254	6,418,039
Less: debt issuance costs	45,214	46,982
Long-term debt, excluding current portion, net of debt issuance costs	6,456,040	6,371,057
Commitments and contingencies (See Note 14)
Current liabilities:
Current portion of long-term debt	218,619	199,356
Loans payable	131,832	228,500
Accounts payable	191,924	238,843
Book overdraft	19,688	28,694
Accrued interest	81,429	47,063
Accrued taxes	29,113	34,393
Liabilities related to assets held for sale	2,669	3,263
Regulatory liabilities	80,190	35,276
Dividends payable		75,808
Other accrued liabilities	141,104	130,673
Total current liabilities	896,568	1,021,869
Deferred credits and other liabilities:
Deferred income taxes and investment tax credits	1,486,979	1,345,766
Customers' advances for construction	129,139	114,732
Regulatory liabilities	825,659	778,754
Asset retirement obligations	845	843
Operating lease liabilities	35,133	37,666
Non-current liabilities related to assets held for sale	758	974
Pension and other postretirement benefit liabilities	32,380	31,244
Other	24,326	28,562
Total deferred credits and other liabilities	2,535,219	2,338,541
Contributions in aid of construction	622,409	610,254
Total liabilities and equity	$ 16,432,793	$ 15,719,107