Equipment, Office Facilities, and Property (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	$ 2,929	$ 2,580
Accumulated depreciation and amortization	(1,890)	(1,790)
Total equipment, office facilities, and property - net	1,039	790
Software [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	1,281	1,177
Buildings [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	673	460
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	310	300
Information technology equipment [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	257	245
Furniture and equipment [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	154	131
Telecommunications equipment [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	83	102
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	64	95
Land [Member]
Property Plant And Equipment [Line Items]
Total equipment, office facilities, and property	$ 107	$ 70