Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets
Property, plant and equipment, at cost	$ 6,590,830	$ 6,509,117
Less: accumulated depreciation	1,533,004	1,507,502
Net property, plant and equipment	5,057,826	5,001,615
Current assets:
Cash and cash equivalents	4,425	3,763
Accounts receivable and unbilled revenues, net	89,409	97,394
Inventory, materials and supplies	13,977	12,961
Prepayments and other current assets	12,727	12,804
Assets held for sale	1,925	1,728
Total current assets	122,463	128,650
Regulatory assets	974,853	948,647
Deferred charges and other assets, net	31,192	30,845
Investment in joint venture	6,995	7,026
Goodwill	42,266	42,208
Total assets	6,235,595	6,158,991
Stockholders' equity:
Common stock at $.50 par value, authorized 300,000,000 shares, issued 180,566,113 and 180,311,345 as of March 31, 2017 and December 31, 2016	90,283	90,155
Capital in excess of par value	800,420	797,513
Retained earnings	1,048,963	1,032,844
Treasury stock, at cost, 2,983,005 and 2,916,969 shares as of March 31, 2017 and December 31, 2016	(73,166)	(71,113)
Accumulated other comprehensive income	727	669
Total stockholders' equity	1,867,227	1,850,068
Long-term debt, excluding current portion	1,819,568	1,759,962
Less: debt issuance costs	22,057	22,357
Long-term debt, excluding current portion, net of debt issuance costs	1,797,511	1,737,605
Commitments and contingencies (See Note 13)
Current liabilities:
Current portion of long-term debt	119,296	150,671
Loans payable	27,732	6,535
Accounts payable	50,185	59,872
Accrued interest	20,624	18,367
Accrued taxes	24,092	25,607
Other accrued liabilities	35,671	40,484
Total current liabilities	277,600	301,536
Deferred credits and other liabilities:
Deferred income taxes and investment tax credits	1,301,189	1,269,253
Customers' advances for construction	90,391	91,843
Regulatory liabilities	245,294	250,635
Other	110,097	115,583
Total deferred credits and other liabilities	1,746,971	1,727,314
Contributions in aid of construction	546,286	542,468
Total liabilities and equity	$ 6,235,595	$ 6,158,991

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Balance Type:	credit
Period Type:	instant

- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.