v2.4.0.6
Netting Financial Assets (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Total [Domain]
    
Gross Amounts of Recognized Assets $ 6,832,800 $ 5,798,900
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 6,832,800 5,798,900
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) (3,092,400) (2,965,800)
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) (3,740,400) (2,833,100)
Net Amount 0 0
Securities Borrowed [Member]
    
Gross Amounts of Recognized Assets 3,740,400 2,833,100
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 3,740,400 2,833,100
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) 0 0
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) (3,740,400) (2,833,100)
Net Amount 0 0
Securities Purchased Under Agreement to Resell [Member]
    
Gross Amounts of Recognized Assets 461,900 428,900
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 461,900 428,900
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) (461,900) (428,900)
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount 0 0
Options owned [Member]
    
Gross Amounts of Recognized Assets 2,477,100 2,388,200
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 2,477,100 2,388,200
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) (2,477,100) (2,388,200)
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount 0 0
Warrants and discount certificates owned [Member]
    
Gross Amounts of Recognized Assets 153,400 147,300
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 153,400 147,300
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) (153,400) (147,300)
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount 0 0
Currency forward contracts owned [Member]
    
Gross Amounts of Recognized Assets 0 1,400
Gross Amounts Assets Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Assets Presented in the Statement of Financial Condition 0 1,400
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Financial Instruments) 0 (1,400)
Gross Amounts of Assets Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Received) 0 0
Net Amount $ 0 $ 0