Income Taxes (Components Of Consolidated Deferred Tax Liabilities (Assets)) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Depreciation and other basis differences related to plant and equipment	$ 1,871	$ 1,680
Deferred electric service and electric restructuring liabilities	131	154
Cross-border energy lease investments	793	816
Federal and state net operating losses	(220)	(46)
Valuation allowances on state net operating losses	21	21
Pension and other postretirement benefits	130	70
Deferred taxes on amounts to be collected through future rates	47	43
Other	32	(113)
Total Deferred Tax Liabilities, net	2,805	2,625
Deferred tax assets included in Current Assets	59	90
Deferred tax liabilities included in Other Current Liabilities	(1)	(1)
Total Consolidated Deferred Tax Liabilities, net non-current	$ 2,863	$ 2,714