Goodwill And Other Intangibles (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2013 Risk and Insurance Services Segment [Member]	Sep. 30, 2012 Risk and Insurance Services Segment [Member]	Dec. 31, 2013 Risk and Insurance Services Segment [Member]	Dec. 31, 2013 Consulting Segment [Member]
Segment Reporting Information [Line Items]
Goodwill acquired	$ 113	$ 226				$ 96	$ 17
Goodwill expected to be tax deductible	7
Goodwill	6,893	6,792	6,562			4,700	2,200
Intangible asset impairment charge	5	8	0	5	8
Finite lived assets amortization expense	$ 72	$ 72	$ 65