Expenses (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended			12 Months Ended			42 Months Ended	6 Months Ended	12 Months Ended				3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended		3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Other Expense [Member]	Jun. 30, 2012 Other Expense [Member]	Jun. 30, 2013 Other Expense [Member]	Jun. 30, 2012 Other Expense [Member]	Jun. 30, 2013 Business Operations And Information Technology Transformation Program	Dec. 31, 2012 Business Operations And Information Technology Transformation Program	Dec. 31, 2011 Business Operations And Information Technology Transformation Program	Dec. 31, 2010 Business Operations And Information Technology Transformation Program	Jun. 30, 2013 Business Operations And Information Technology Transformation Program	Jun. 30, 2013 Business Operations And Information Technology Transformation Program Involuntary Terminations [Member] employee	Dec. 31, 2011 Business Operations And Information Technology Transformation Program Involuntary Terminations [Member] employee	Dec. 31, 2010 Business Operations And Information Technology Transformation Program Involuntary Terminations [Member] employee	Dec. 31, 2011 Expenses Control Measures	Dec. 31, 2011 Expenses Control Measures Involuntary Terminations [Member] employee	Jun. 30, 2013 Expenses Control Measures - Additional Targeted Staff Reductions	Jun. 30, 2013 Expenses Control Measures - Additional Targeted Staff Reductions	Dec. 31, 2012 Expenses Control Measures - Additional Targeted Staff Reductions	Dec. 31, 2012 Expenses Control Measures - Additional Targeted Staff Reductions Involuntary Terminations [Member] employee	Jun. 30, 2013 Expenses Control Measures - Additional Targeted Staff Reductions Involuntary Terminations [Member] employee	Dec. 31, 2012 Expenses Control Measures - Additional Targeted Staff Reductions Involuntary Terminations After Replacements [Member] employee
Business Acquisition [Line Items]
Restructuring charges, net	$ 11	$ 22	$ 10	$ 30					$ 8	$ 67	$ 133	$ 156	$ 364				$ 120		$ 11	$ 2	$ 133
Expected number of positions eliminated														212	1,187	1,400		442				960		630
Percent of actual number of positions eliminated																5.00%
Number of positions eliminated from inception to date														1,115									638
Charitable contributions					$ 34	$ 2	$ 35	$ 3