v2.4.0.6
Summary of Changes in Financial Assets Measured at Fair Value for Which Level III Inputs Were Used (Detail) (Level 3, USD $)
In Thousands, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Balance, Beginning of Period $ 2,517,071 $ 1,776,696 $ 2,132,488 $ 1,753,333
Transfer In Due to Consolidation and Acquisition   9,570 [1] 122,565 [1] 9,570 [1]
Transfer Out Due to Deconsolidation (1,599)   (1,599)  
Transfer In to Level III 171,916 [2] 4,607 [2] 253,608 [2] 11,162 [2]
Transfer Out of Level III (59,315) [2] (112,780) [2] (103,280) [2] (134,243) [2]
Purchases 272,441 545,491 463,320 679,819
Sales (215,929) (163,111) (279,415) (348,257)
Settlements (186) 4,862 (46) (1,441)
Realized Gains (Losses), Net (11,723) (3,233) (8,454) 4,618
Changes in Unrealized Gains (Losses) Included in Earnings Related to Investments Still Held at the Reporting Date (6,951) 41,572 86,538 129,113
Balance, End of Period 2,665,725 2,103,674 2,665,725 2,103,674
Investments Of Consolidated Funds
        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Balance, Beginning of Period 2,390,276 1,741,692 2,103,769 1,602,371
Transfer In Due to Consolidation and Acquisition   9,570 [1] 122,565 [1] 9,570 [1]
Transfer Out Due to Deconsolidation (1,599)   (1,599)  
Transfer In to Level III 171,916 [2] 4,607 [2] 253,608 [2] 11,162 [2]
Transfer Out of Level III (59,315) [2] (112,780) [2] (103,280) [2] (134,243) [2]
Purchases 232,684 308,430 320,312 436,529
Sales (173,516) (154,861) (229,623) (217,826)
Settlements   4,933    
Realized Gains (Losses), Net (12,264) (3,764) (9,093) 4,087
Changes in Unrealized Gains (Losses) Included in Earnings Related to Investments Still Held at the Reporting Date (8,026) 40,026 83,497 126,203
Balance, End of Period 2,540,156 1,837,853 2,540,156 1,837,853
Loans And Receivables
        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Balance, Beginning of Period 105,004 14,034 8,555 131,290
Purchases 39,657 119,861 142,908 126,090
Sales (41,872) (7,719) (49,251) (129,900)
Settlements (186) (71) (46) (1,441)
Changes in Unrealized Gains (Losses) Included in Earnings Related to Investments Still Held at the Reporting Date 1,604 1,003 2,041 1,069
Balance, End of Period 104,207 127,108 104,207 127,108
Other Investments
        
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]        
Balance, Beginning of Period 21,791 20,970 20,164 19,672
Purchases 100 117,200 100 117,200
Sales (541) (531) (541) (531)
Realized Gains (Losses), Net 541 531 639 531
Changes in Unrealized Gains (Losses) Included in Earnings Related to Investments Still Held at the Reporting Date (529) 543 1,000 1,841
Balance, End of Period $ 21,362 $ 138,713 $ 21,362 $ 138,713
[1] Represents the transfer into Level III of financial assets and liabilities held by CLO vehicles as a result of the acquisition of management contracts on May 16, 2011 and the Harbourmaster acquisition on January 5, 2012.
[2] Transfers in and out of Level III financial assets and liabilities were due to changes in the observability of inputs used in the valuation of such assets and liabilities.