v2.4.0.6
Business Combinations (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Pending Acquisition [Member]
Dec. 31, 2011
Acquisitions of insurance brokerage businesses [Member]
Dec. 31, 2010
Acquisitions of insurance brokerage businesses [Member]
Dec. 31, 2012
EverKey Global Partners Limited/EverKey Global Management LLC/EverKey Global Partners (GP), LLC/EverKey Global Focus (GP), LLC - Bahamas/New York, New York [Member]
Dec. 31, 2012
Burdale Financial Holdings Limited/Certain Assets of Burdale Capital Finance, Inc. - England/Stamford, Connecticut [Member]
Dec. 31, 2012
Energy Lending Business of BNP Paribas, SA - Houston, Texas [Member]
Dec. 31, 2012
Merlin Securities, LLC/Merlin Canada LTD./Certain Assets & Liabilities of Merlin Group Holdings, LLC - San Francisco, California/Toronto, Ontario [Member]
Dec. 31, 2011
CP Equity, LLC - Denver, Colorado [Member]
Dec. 31, 2011
Certain assets of Foreign Current Exchange Corp - Orlando, Florida [Member]
Dec. 31, 2011
LaCrosse Holdings, LLC - Minneapolis, Minnesota [Member]
Dec. 31, 2010
Certain assets of GMAC Commercial Finance, LLC - New York, New York [Member]
Business Acquisition [Line Items]                            
Date             Jan. 01, 2012 Feb. 01, 2012 Apr. 20, 2012 Aug. 01, 2012 Jul. 01, 2011 Aug. 01, 2011 Nov. 30, 2011 Apr. 30, 2010
Various Dates         Various Various                
Business Acquisition, Number Completed during period       0 7 5                
Business Acquisition, Purchase Price Allocation, Assets Acquired $ 4,801 $ 588 $ 470   $ 37 $ 40 $ 7 $ 874 $ 3,639 $ 281 $ 389 $ 46 $ 116 $ 430