Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Nuclear fuel; fuel in process	$ 43,443	$ 47,746
Accounts receivable, principally trade, allowance for doubtful accounts	$ 2,799	$ 2,885
Common stock, stated value	$ 1.00	$ 1.00
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	65,264,664	65,121,689
Common stock, restricted shares	196,954	143,371
Treasury stock, shares	25,212,530	22,693,995