Environmental Matters (Accrued Liability For Asbestos Suits And Workers' Compensation Proceedings) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Site Contingency [Line Items]
Regulatory assets	$ 9,501	$ 7,886
Asbestos Suits [Member]
Site Contingency [Line Items]
Accrued liability	10	10
Regulatory assets	10	10
Workers' Compensation [Member]
Site Contingency [Line Items]
Accrued liability	98	106
Regulatory assets	$ 23	$ 31