Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets
Property, plant and equipment, at cost	$ 15,208,072	$ 14,977,021
Less: accumulated depreciation	2,952,487	2,879,949
Net property, plant and equipment	12,255,585	12,097,072
Current assets:
Cash and cash equivalents	35,200	4,612
Accounts receivable, net	164,638	144,300
Unbilled revenues	102,793	101,436
Inventory - materials and supplies	48,947	47,494
Inventory - gas stored	17,849	65,173
Prepayments and other current assets	34,619	99,884
Regulatory assets	15,488	29,080
Total current assets	419,534	491,979
Regulatory assets	1,899,984	1,766,892
Deferred charges and other assets, net	97,865	102,388
Funds restricted for construction activity	1,391	1,381
Goodwill	2,340,733	2,340,738
Operating lease right-of-use assets	35,739	37,416
Intangible assets	3,513	3,593
Total assets	17,054,344	16,841,459
Stockholders' equity:
Common stock at $0.50 par value, authorized 600,000,000 shares, issued 276,878,103 and 276,595,228 as of March 31, 2024 and December 31, 2023	138,438	138,297
Capital in excess of par value	4,142,610	4,137,696
Retained earnings	1,888,521	1,706,675
Treasury stock, at cost, 3,354,887 and 3,299,191 shares as of March 31, 2024 and December 31, 2023	(88,442)	(86,485)
Total stockholders' equity	6,081,127	5,896,183
Long-term debt, excluding current portion	6,903,544	6,870,593
Less: debt issuance costs	47,415	44,508
Long-term debt, excluding current portion, net of debt issuance costs	6,856,129	6,826,085
Commitments and contingencies (See Note 14)
Current liabilities:
Current portion of long-term debt	67,247	67,415
Loans payable	87,500	160,123
Accounts payable	161,210	221,191
Book overdraft	10,938	13,358
Accrued interest	86,512	53,084
Accrued taxes	36,911	40,641
Regulatory liabilities	14,216	31,270
Dividends payable	83,999	83,929
Other accrued liabilities	130,073	126,916
Total current liabilities	678,606	797,927
Deferred credits and other liabilities:
Deferred income taxes and investment tax credits	1,733,947	1,628,324
Customers' advances for construction	125,191	128,755
Regulatory liabilities	838,084	820,910
Asset retirement obligations	851	848
Operating lease liabilities	32,415	34,425
Pension and other postretirement benefit liabilities	37,363	38,850
Other	23,699	24,086
Total deferred credits and other liabilities	2,791,550	2,676,198
Contributions in aid of construction	646,932	645,066
Total liabilities and equity	$ 17,054,344	$ 16,841,459