Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	$ 26	$ 8
Tax benefit associated with stock-based compensation	10	3
Stock-based compensation cost capitalized	1	0
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	2	2
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	13	8
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	$ 11	$ (2)