v2.4.0.6
Netting Financial Liabilities (Detail) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Total [Domain]
    
Gross Amounts of Recognized Liabilities $ 4,671,400 $ 4,234,900
Gross Amounts Liabilities Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Liabilities Presented in the Statement of Financial Condition 4,671,400 4,234,900
Gross Amounts of Liabilities Not Offset in the Condensed Consolidated Satement of Financial Position (Financial Instruments) (2,472,600) (2,395,600)
Gross Amounts Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Pledged) (2,198,800) (1,839,300)
Net Amount 0 0
Securities Loaned [Member]
    
Gross Amounts of Recognized Liabilities 2,198,800 1,839,300
Gross Amounts Liabilities Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Liabilities Presented in the Statement of Financial Condition 2,198,800 1,839,300
Gross Amounts of Liabilities Not Offset in the Condensed Consolidated Satement of Financial Position (Financial Instruments) 0 0
Gross Amounts Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Pledged) (2,198,800) (1,839,300)
Net Amount 0 0
Options Sold, Not Yet Purchased [Member]
    
Gross Amounts of Recognized Liabilities 2,465,000 2,389,900
Gross Amounts Liabilities Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Liabilities Presented in the Statement of Financial Condition 2,465,000 2,389,900
Gross Amounts of Liabilities Not Offset in the Condensed Consolidated Satement of Financial Position (Financial Instruments) (2,465,000) (2,389,900)
Gross Amounts Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Pledged) 0 0
Net Amount 0 0
Warrants and discount certificates sold, not yet purchased [Member]
    
Gross Amounts of Recognized Liabilities 3,200 2,100
Gross Amounts Liabilities Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Liabilities Presented in the Statement of Financial Condition 3,200 2,100
Gross Amounts of Liabilities Not Offset in the Condensed Consolidated Satement of Financial Position (Financial Instruments) (3,200) (2,100)
Gross Amounts Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Pledged) 0 0
Net Amount 0 0
Currency forward contracts sold, not yet purchased [Member]
    
Gross Amounts of Recognized Liabilities 4,400 3,600
Gross Amounts Liabilities Offset in the Condensed Consolidated Statement of Financial Condition 0 0
Net Amounts of Liabilities Presented in the Statement of Financial Condition 4,400 3,600
Gross Amounts of Liabilities Not Offset in the Condensed Consolidated Satement of Financial Position (Financial Instruments) (4,400) (3,600)
Gross Amounts Not Offset in the Condensed Consolidated Statement of Financial Position (Cash Collateral Pledged) 0 0
Net Amount $ 0 $ 0