Employee Postretirement Benefits (Narrative) (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Mar. 31, 2010	Jun. 30, 2011
Cash contributions to pension trusts	$ 150,000,000	$ 265,000,000	$ 52,000,000	$ 176,000,000
Percentage of equity collars in place on equity allocation	50.00%				50.00%
Equity collars on defined benefit plans	1,800,000,000				1,800,000,000
Defined Benefits Plans Treasury Future					420,000,000
Minimum [Member]
Anticipated contribution to pension trust for the full year	420,000,000				420,000,000
Maximum [Member]
Anticipated contribution to pension trust for the full year	$ 500,000,000				$ 500,000,000