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Equity Method Investments in Affiliates (Details) (USD $) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Schedule of Equity Method Investments |  |  |  |
Amortization expense during the period | $ 24,000,000 | $ 22,100,000 | $ 169,100,000 | $ 66,300,000
Annual amortization expense attributable to current equity method Affiliates for next five years |  |  |  |
2012 | 37,800,000 |  | 37,800,000 |
2013 | 44,900,000 |  | 44,900,000 |
2014 | 23,500,000 |  | 23,500,000 |
2015 | 14,900,000 |  | 14,900,000 |
2016 | 12,400,000 |  | 12,400,000 |
Blue Mountain Capital Management |  |  |  |
Schedule of Equity Method Investments |  |  |  |
Value of managed assets | 8,000,000,000 |  | 8,000,000,000 |
Purchase price allocated to acquired client relationship | 122,800,000 |  | 122,800,000 |
Period of consideration paid |  |  | 15 years |
Client relationship |  |  |  |
Schedule of Equity Method Investments |  |  |  |
Weighted average life |  |  | 11 years |
Amortization expense during the period | 24,000,000 | 22,100,000 | 66,900,000 | 66,300,000
Acquired client relationships under equity method investments |  |  |  |
Schedule of Equity Method Investments |  |  |  |
Weighted average life |  |  | 8 years |
Amortization expense during the period | $ 10,200,000 | $ 8,200,000 | $ 26,500,000 | $ 24,800,000

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