Fiduciary Assets And Liabilities (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Risk and Insurance Services [Member]	Sep. 30, 2011 Risk and Insurance Services [Member]	Sep. 30, 2012 Consulting [Member]	Sep. 30, 2011 Consulting [Member]
Interest on fiduciary funds			$ 31	$ 36	$ 2	$ 3
Fixed income securities in fiduciary assets	5	62
Unrealized gains, net of tax	0	2
Net uncollected premiums and claims receivable and payable	10,000	9,000
Assets in trusts or funds for management or trustee fee					$ 16,000