Consolidated Balance Sheets (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Property plant and equipment    
Utility plant—at original cost, net of accumulated depreciation of $4,062,270 at March 31 and $3,991,680 at December 31 $ 12,985,631 $ 12,899,704
Nonutility property, net of accumulated depreciation of $239,246 at March 31 and $248,341 at December 31 112,936 129,592
Total property, plant and equipment 13,098,567 13,029,296
Current assets    
Cash and cash equivalents 24,294 23,080
Restricted funds 21,027 13,859
Accounts receivable 267,204 267,053
Allowance for uncollectible accounts (35,485) (34,941)
Unbilled revenues 222,111 220,538
Income taxes receivable 8,014 2,575
Materials and supplies 38,622 37,190
Deferred income taxes 119,839 86,601
Other 63,393 45,414
Total current assets 729,019 661,369
Regulatory and other long-term assets    
Regulatory assets 1,151,849 1,153,429
Restricted funds 8,796 8,958
Goodwill 1,208,043 1,208,043
Other 67,257 69,861
Total regulatory and other long-term assets 2,435,945 2,440,291
TOTAL ASSETS 16,263,531 16,130,956
Capitalization    
Common stock ($0.01 par value, 500,000 shares authorized, 179,921 shares outstanding at March 31 and 179,462 at December 31) 1,799 1,795
Paid-in-capital 6,313,242 6,301,729
Accumulated deficit (1,224,008) (1,295,549)
Accumulated other comprehensive loss (81,503) (81,868)
Treasury stock (16,592) (10,516)
Total common stockholders' equity 4,992,938 4,915,591
Long-term debt 5,428,901 5,432,744
Redeemable preferred stock at redemption value 14,296 15,501
Total capitalization 10,436,135 10,363,836
Current liabilities    
Short-term debt 544,531 449,959
Current portion of long-term debt 61,149 61,132
Accounts payable 203,409 285,800
Taxes accrued 55,714 24,505
Interest accrued 94,934 56,523
Other 267,811 363,079
Total current liabilities 1,227,548 1,240,998
Regulatory and other long-term liabilities    
Advances for construction 362,722 367,693
Deferred income taxes 2,199,681 2,120,739
Deferred investment tax credits 24,676 25,014
Regulatory liabilities 386,317 391,782
Accrued pension expense 317,444 316,368
Accrued postretirement benefit expense 191,689 192,502
Other 36,059 37,152
Total regulatory and other long-term liabilities 3,518,588 3,451,250
Contributions in aid of construction 1,081,260 1,074,872
Commitments and contingencies (See Note 9)      
TOTAL CAPITALIZATION AND LIABILITIES $ 16,263,531 $ 16,130,956