Common Equity (Details)	12 Months Ended
	Dec. 31, 2005	Dec. 31, 2011 Treasury Stock [Member]	Dec. 31, 2010 Treasury Stock [Member]	Dec. 31, 2009 Treasury Stock [Member]	Dec. 31, 2009 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2010 Common Stock [Member]
Common stock and treasury stock shares activity
Beginning Balance, Shares		76,006,920	65,634,580	58,815,518	248,174,087	254,752,788	254,752,788
Equity Unit Transaction	10,000,000				6,578,701
Repurchases, shares		3,475,000	11,490,551	7,680,000
Issuances :
Employee Stock-Based Compensation Plans		(1,079,008)	(1,113,411)	(856,390)
Directors Plan		(5,924)	(4,800)	(4,548)
Ending Balance, Shares		78,396,988	76,006,920	65,634,580	254,752,788	254,752,788	254,752,788