Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Pre-tax stock-based compensation	$ 11	[1],[2]	$ 11	[1],[2]	$ 19	[3],[4]	$ 27	[3],[4]
Tax benefit associated with stock-based compensation	4		5		7		11
Stock-based compensation cost capitalized	1		1		1		2
Stock Options [Member]
Pre-tax stock-based compensation	0		0		2		2
Restricted Stock Units Awards [Member]
Pre-tax stock-based compensation	6		6		14		14
Performance Awards [Member]
Pre-tax stock-based compensation	$ 5		$ 5		$ 3		$ 11

[1] Excludes stock-based compensation cost capitalized of $1 million for each of the three months ended June 30, 2012 and 2011.

[2] The tax benefit associated with the recorded expense was $4 million and $5 million for the three months ended June 30, 2012 and 2011, respectively.

[3] Excludes stock-based compensation cost capitalized of $1 million and $2 million for the six months ended June 30, 2012 and 2011, respectively.

[4] The tax benefit associated with the recorded expense was $7 million and $11 million for the six months ended June 30, 2012 and 2011, respectively.