Commitments and Contingent Liabilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Rent expense [Abstract]
Rent expense	$ 83	$ 86	$ 88
Office facilities [Member]
Rent expense [Abstract]
Rent expense	73	77	75
Equipment [Member]
Rent expense [Abstract]
Rent expense	$ 10	$ 9	$ 13

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

No definition available.

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration