Equipment, Office Facilities, and Property (Schedule of Equipment, Office Facilities, and Property) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	$ 2,932	$ 2,929
Accumulated depreciation and amortization	(1,787)	(1,890)
Total equipment, office facilities, and property - net	1,145	1,039
Software [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	1,183	1,281
Buildings [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	771	673
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	322	310
Information technology equipment [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	273	257
Equipment and Office Facilities [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	177	154
Telecommunications equipment [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	78	83
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	18	64
Land [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	$ 110	$ 107