Consolidated Balance Sheets (USD $) In Thousands	3 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Utility plant:
Electric plant in service	$ 2,718,910	$ 2,522,862
Less accumulated depreciation and amortization	(1,085,881)	(1,047,498)
Net plant in service	1,633,029	1,475,364
Construction work in progress	161,080	285,086
Nuclear fuel; includes fuel in process of $33,209 and $47,746, respectively	164,815	150,774
Less accumulated amortization	(51,617)	(45,471)
Net nuclear fuel	113,198	105,303
Net utility plant	1,907,307	1,865,753
Current assets:
Cash and cash equivalents	5,106	79,184
Accounts receivable, principally trade, net of allowance for doubtful accounts of $2,267 and $2,885, respectively	107,457	71,685
Accumulated deferred income taxes	11,185	25,818
Inventories, at cost	38,415	36,132
Income taxes receivable	2,508	12,656
Undercollection of fuel revenues	6,851	0
Prepayments and other	9,804	4,543
Total current assets	181,326	230,018
Deferred charges and other assets:
Decommissioning trust funds	162,702	153,878
Regulatory assets	88,107	88,557
Other	28,030	26,560
Total deferred charges and other assets	278,839	268,995
Total assets	2,367,472	2,364,766
Capitalization:
Common stock, stated value $1 per share, 100,000,000 shares authorized, 65,241,772 and 65,121,689 shares issued, and 199,619 and 143,371 restricted shares, respectively	65,441	65,265
Capital in excess of stated value	306,926	305,068
Retained earnings	841,375	810,858
Accumulated other comprehensive loss, net of tax	(30,981)	(33,177)
Total stockholders equity subtotal before treasury stock	1,182,761	1,148,014
Treasury stock, 23,621,213 and 22,693,995 shares, respectively, at cost	(364,459)	(337,639)
Common stock equity	818,302	810,375
Long-term debt	849,771	849,745
Total capitalization	1,668,073	1,660,120
Current liabilities:
Short-term borrowings under the revolving credit facility	39,642	4,704
Accounts payable, principally trade	52,700	41,795
Taxes accrued	25,350	29,172
Interest accrued	12,108	12,099
Overcollection of fuel revenues	0	18,976
Other	22,795	24,207
Total current liabilities	152,595	130,953
Deferred credits and other liabilities:
Accumulated deferred income taxes	287,765	286,730
Accrued pension liability	83,918	93,471
Asset retirement obligation	69,295	92,911
Accrued postretirement benefit liability	62,683	61,594
Regulatory liabilities	15,007	14,489
Other	28,136	24,498
Total deferred credits and other liabilities	546,804	573,693
Commitments and contingencies
Total capitalization and liabilities	$ 2,367,472	$ 2,364,766