Income Taxes (Schedule Of Deferred Tax Assets For Loss And Tax Credit Carryforwards) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Income Taxes [Line Items]
Net operating losses	$ 825
Capital losses	10
Tax credits	1,088
Totals as of December 31, 2012	1,923
2013 - 2017 [Member]
Income Taxes [Line Items]
Net operating losses	97
Capital losses	10
Tax credits	150
Totals as of December 31, 2012	257
2018 - 2022 [Member]
Income Taxes [Line Items]
Net operating losses	163
Tax credits	778
Totals as of December 31, 2012	941
2023 - 2032 [Member]
Income Taxes [Line Items]
Net operating losses	360
Tax credits	114
Totals as of December 31, 2012	474
Indefinite [Member]
Income Taxes [Line Items]
Net operating losses	205
Tax credits	46
Totals as of December 31, 2012	$ 251