Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Estimated fair value of stock based compensation awards allocated to purchase price.			$ 62				$ 62
Pre-tax stock-based compensation	32	[1],[2]	12	[2],[3]	51	[1],[3],[4]	39	[1],[3],[4]
Tax benefit associated with stock-based compensation	13		5		20		16
Stock-based compensation cost capitalized	0		1		1		3
Stock Options [Member]
Pre-tax stock-based compensation	0		0		2		2
Restricted Stock Units Awards [Member]
Pre-tax stock-based compensation	16		6		30		20
Performance Awards [Member]
Pre-tax stock-based compensation	$ 16		$ 6		$ 19		$ 17

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

[2] The tax benefit associated with the recorded expense was $13 million and $5 million for the three months ended September 30, 2012 and 2011, respectively.

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

[4] The tax benefit associated with the recorded expense was $20 million and $16 million for the nine months ended September 30, 2012 and 2011, respectively.