Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Utility plant:
Electric plant in service	$ 3,014,517	$ 2,857,913
Less accumulated depreciation and amortization	(1,186,206)	(1,162,483)
Net plant in service	1,828,311	1,695,430
Construction work in progress	224,519	287,358
Nuclear fuel; includes fuel in process of $54,004 and $56,129, respectively	191,892	189,921
Less accumulated amortization	(75,058)	(70,366)
Net nuclear fuel	116,834	119,555
Net utility plant	2,169,664	2,102,343
Current assets:
Cash and cash equivalents	11,646	111,057
Accounts receivable, principally trade, net of allowance for doubtful accounts of $2,303 and $2,906, respectively	106,526	62,900
Accumulated deferred income taxes	27,993	20,292
Inventories, at cost	43,898	42,358
Undercollection of fuel revenues	4,297	0
Prepayments and other	13,216	9,627
Total current assets	207,576	246,234
Deferred charges and other assets:
Decommissioning trust funds	196,166	187,053
Regulatory assets	102,375	101,590
Other	32,519	31,830
Total deferred charges and other assets	331,060	320,473
Total assets	2,708,300	2,669,050
Capitalization:
Common stock, stated value $1 per share, 100,000,000 shares authorized, 65,624,223 and 65,520,551 shares issued, and 118,953 and 84,446 restricted shares, respectively	65,743	65,605
Capital in excess of stated value	312,684	310,994
Retained earnings	955,244	939,131
Accumulated other comprehensive loss, net of tax	(60,597)	(66,084)
Total stockholders equity subtotal before treasury stock	1,273,074	1,249,646
Treasury stock, 25,492,919 shares at cost	(424,647)	(424,647)
Common stock equity	848,427	824,999
Long-term debt	999,576	999,535
Total capitalization	1,848,003	1,824,534
Current liabilities:
Short-term borrowings under the revolving credit facility	26,319	22,155
Accounts payable, principally trade	53,643	61,581
Taxes accrued	25,521	29,248
Interest accrued	12,200	12,127
Overcollection of fuel revenues	0	4,643
Other	23,072	21,995
Total current liabilities	140,755	151,749
Deferred credits and other liabilities:
Accumulated deferred income taxes	388,454	358,674
Accrued pension liability	112,821	125,690
Accrued postretirement benefit liability	101,170	99,170
Asset retirement obligation	65,717	62,784
Regulatory liabilities	23,985	22,179
Other	27,395	24,270
Total deferred credits and other liabilities	719,542	692,767
Commitments and contingencies
Total capitalization and liabilities	$ 2,708,300	$ 2,669,050