Derivative Financial Instruments And Fair Value Measurements (Summary Of Various Interest Rate Agreements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
4.91% [Member]
Derivative [Line Items]
Expiration Date	Mar. 30, 2012
Notional Amounts	$ 1,250
4.91% [Member] | Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Fixed Interest Rates	4.91%
0.415% To 0.418% [Member]
Derivative [Line Items]
Notional Amounts	900	[1]
Notional Amounts Decrease	400
0.415% To 0.418% [Member] | Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Fixed Interest Rates, Low	0.415%	[1]
Fixed Interest Rates, High	0.418%	[1]
1.60% To 1.84% [Member]
Derivative [Line Items]
Expiration Date	Dec. 31, 2013	[2]
Notional Amounts	800	[2]
1.60% To 1.84% [Member] | Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Fixed Interest Rates, Low	1.60%
Fixed Interest Rates, High	1.84%
2.75% To 2.84% [Member]
Derivative [Line Items]
Expiration Date	Mar. 31, 2016	[2]
Notional Amounts	200	[2]
2.75% To 2.84% [Member] | Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Fixed Interest Rates, Low	2.75%
Fixed Interest Rates, High	2.84%
2.70% To 3.17% [Member]
Derivative [Line Items]
Expiration Date	Mar. 31, 2017	[2]
Notional Amounts	$ 650	[2]
2.70% To 3.17% [Member] | Interest Rate Swap Contracts [Member]
Derivative [Line Items]
Fixed Interest Rates, Low	2.70%
Fixed Interest Rates, High	3.17%
Minimum [Member] | 0.415% To 0.418% [Member]
Derivative [Line Items]
Expiration Date	Mar. 30, 2012
Maximum [Member] | 0.415% To 0.418% [Member]
Derivative [Line Items]
Expiration Date	Dec. 30, 2012

[1] In September 2011, we entered into forward-starting interest rate swap agreements with an effective date of December 30, 2011. The notional amounts of the swap agreements decrease by $400 million on March 30, 2012 and the remaining notional amounts expire on December 30, 2012.

[2] In August 2010 and April 2011, we entered into forward-starting interest rate swap agreements with an effective date of March 30, 2012.