v2.4.0.8
Financial Assets And Financial Liabilities (Netting of Financial Assets) (Details) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2014
Dec. 31, 2013
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets $ 10,803.6 $ 11,815.6
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 10,803.6 11,815.6
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (10,640.3) (11,469.1)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 163.3 346.5
Securities Segregated For Regulatory Purposes - Purchased Under Agreements To Resell [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 5,913.9 [1] 6,734.2 [1]
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 5,913.9 6,734.2
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (5,913.9) (6,734.2)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 0 0
Securities Borrowed [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 3,499.2 2,751.5
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 3,499.2 2,751.5
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (3,419.0) (2,694.6)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 80.2 56.9
Securities Purchased Under Agreement to Resell [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 274.3 386.3
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 274.3 386.3
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (274.3) (386.3)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 0 0
Options [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 1,073.0 1,880.5
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 1,073.0 1,880.5
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (1,032.5) (1,652.8)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 40.5 227.7
Warrants And Discount Certificates [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 34.6 57.4
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 34.6 57.4
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) (0.6) (1.2)
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets 34.0 56.2
Currency Forward Contracts [Member]
    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets 8.6 5.7
Gross Amounts Assets Offset in the Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 8.6 5.7
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Financial Instruments) 0 0
Gross Amounts of Assets Not Offset in the Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount of Assets $ 8.6 $ 5.7
[1] As of June 30, 2014 and December 31, 2013, the Company had $5.91 billion and $6.73 billion, respectively, of securities purchased under agreements to resell that were segregated to satisfy regulatory requirements. These securities are included in “Cash and securities—segregated for regulatory purposes” in the condensed consolidated statements of financial condition