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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Net income	$ 151	$ 143	$ 290	$ 277
Less income allocated to participating securities	2	2	4	4
Net income attributable to common shares	$ 149	$ 141	$ 286	$ 273
Basic average common shares	179	183	180	184
Basic earnings per common share	$ 0.83	$ 0.77	$ 1.59	$ 1.48
Basic average common shares	179	183	180	184
Net effect of the assumed exercise of stock options	2	1	2	1
Net effect of the assumed exercise of warrants	5	3	4	2
Diluted average common shares	186	187	186	187
Diluted earnings per common share	$ 0.80	$ 0.76	$ 1.54	$ 1.46