Income Taxes (Schedule Of Deferred Tax Assets For Loss And Tax Credit Carryforwards) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Income Taxes [Line Items]
Net operating losses	$ 1,061
Capital losses	4
Tax credits	974
Totals as of December 31, 2011	2,039
2012-2015 [Member]
Income Taxes [Line Items]
Net operating losses	116
Capital losses	4
Tax credits	83
Totals as of December 31, 2011	203
2016-2020 [Member]
Income Taxes [Line Items]
Net operating losses	131
Tax credits	719
Totals as of December 31, 2011	850
2021-2030 [Member]
Income Taxes [Line Items]
Net operating losses	633
Tax credits	103
Totals as of December 31, 2011	736
Indefinite [Member]
Income Taxes [Line Items]
Net operating losses	181
Tax credits	69
Totals as of December 31, 2011	$ 250