Commitments And Contingent Liabilities (Leveraged Lease Investments) (Details) (USD $)	9 Months Ended	12 Months Ended		12 Months Ended
	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2011 Leveraged Lease Investments [Member]	Dec. 31, 2010 Energy Holdings [Member]
Site Contingency [Line Items]
Penalty percentage proposed for substantial understatement of tax liability			20.00%
Reduction in tax exposure				$ 1,100,000,000
Aggregate tax currently payable	266,000,000
Amount deposited with IRS to defray potential interest costs	320,000,000
Penalties from leverage lease investment tax examination	150,000,000
Rate of interest and penalty growth per quarter during 2011	2,000,000
Additional tax potentially due-low estimate	20,000,000
Additional tax potentially due-high estimate	40,000,000
Estimate of tax, interest and penalties potentially payable in 2011 for 1997 to 2000 tax years-low estimate		110,000,000
Estimate of tax, interest and penalties potentially payable in 2011 for 1997 to 2000 tax years-high estimate		300,000,000
Estimate of tax, interest and penalties potentially payable in 2011 for 2001 to 2003 tax years-low estimate		220,000,000
Estimate of tax, interest and penalties potentially payable in 2011 for 2001 to 2003 tax years-high estimate		560,000,000
Earnings impact consistent with broad settlement offer proposed by IRS-low estimate	120,000,000
Earnings impact consistent with broad settlement offer proposed by IRS-high estimate	$ 140,000,000
Income tax examination, description	To date, six cases have been decided at the trial court level, five of which were decided in favor of the government. The appeals of three of these decisions were affirmed, each in favor of the government. The sixth case involves a jury verdict that was challenged by both parties on inconsistency grounds but was later settled by the parties. One case, involving an investment in an energy transaction by a utility, was decided in favor of the taxpayer.