Net Income Per Common Share (Basic And Diluted Net Income Per Common Share) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 154	$ 147	$ 444	$ 424
Less income allocated to participating securities	2	2	6	6
Net income attributable to common shares	$ 152	$ 145	$ 438	$ 418
Basic average common shares	179	182	179	184
Basic earnings per common share	$ 0.85	$ 0.80	$ 2.44	$ 2.28
Basic average common shares	179	182	179	184
Net effect of the assumed exercise of stock options	2	1	2	1
Net effect of the assumed exercise of warrants	4	4	5	2
Diluted average common shares	185	187	186	187
Diluted earnings per common share	$ 0.82	$ 0.78	$ 2.35	$ 2.23