Occupancy Expense And Information Systems And Communications Expense (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 sqft	Dec. 31, 2011	Dec. 31, 2010
Communications, Information Technology and Occupancy [Abstract]
Total depreciation expense	$ 373	$ 368	$ 373
Leased Area, square feet	1,025,000
Underground parking garage, square feet	366,000
Non-cancelable capital leases Period	20 years
Subleased building, square feet	153,000
Non-cancelable lease maturity date	September 2023
Leased area of office building, square feet	362,000
Capital lease period	20 years
Capital lease maturity date	December 2028
Period for cancellation of capital lease	15 years
Net book value of capital leases with the related liability recorded in long term debt	576	565
Interest expense related to capital lease obligations	42	43	44
Accumulated amortization of assets related to capital leases	313	273
Rental expense, net of sublease revenue	227	232	241
Sublease revenue	4	5	5
Future minimum sublease rental commitments for capital lease	25
Future minimum sublease rental commitments for operating lease	$ 13