Retirement Benefits (Changes In Fair Value Measurements Of Level 3 Investments) (Details) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Private Equity Partnerships [Member]		Dec. 31, 2010 Private Equity Partnerships [Member]		Dec. 31, 2011 Insurance Group Annuity Contracts [Member]	Dec. 31, 2009 Insurance Group Annuity Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Beginning balance	$ 8,132	$ 7,773	$ 795	[1]	$ 744		$ 3	$ 3
Relating to assets still held at the reporting date			53		1
Relating to assets sold during the period			48		69
Purchases, sales, settlements (net)					(19)
Purchases			146
Sales			(122)				(1)
Ending balance	$ 8,132	$ 7,773	$ 920	[2]	$ 795	[1]	$ 2	$ 3

[1] Includes limited partnerships that invest primarily in U.S. (92%) and European (8%) buyout opportunities of a range of privately held companies. The Master Trust does not have the right to redeem its limited partnership investment at its net asset value. Instead, the Master Trust receives distributions as the underlying assets are liquidated. It is estimated that the underlying assets of these funds will be gradually liquidated over the next 1 to 10 years. Additionally, the Master Trust has future funding commitments of approximately $389 million over the next 10 years.

[2] Includes limited partnerships that invest primarily in U.S. (92%) and European (8%) buyout opportunities of a range of privately held companies. The Master Trust does not have the right to redeem its limited partnership investment at its net asset value. Instead, the Master Trust receives distributions as the underlying assets are liquidated. It is estimated that the underlying assets of these funds will be gradually liquidated over the next 1 to 10 years. Additionally, the Master Trust has future funding commitments of approximately $335 million over the next 10 years.