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Goodwill and Acquired Client Relationships (Details 2) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2012 | Sep. 30, 2011 | Sep. 30, 2012 | Sep. 30, 2011
Indefinite-lived |  |  |  |
Net book value balance at the beginning of the period |  |  | $ 667.6 |
New investments |  |  | 321.5 |
Amortization and Impairment |  |  | (102.2) |
Foreign currency translation |  |  | 9.4 |
Transfer |  |  | (38.2) |
Net book value balance at the end of the period | 858.1 |  | 858.1 |
Total intangible assets |  |  |  |
Total, Net book value balance at the beginning of the period |  |  | 1,321.1 |
Total, New investments |  |  | 452.6 |
Total, Amortization and Impairment |  |  | (169.1) |
Total, Foreign currency translation |  |  | 10.7 |
Total, Net book value balance at the end of the period | 1,615.3 |  | 1,615.3 |
Amortization expenses |  |  |  |
Amortization expense during the period | 24.0 | 22.1 | 169.1 | 66.3
Acquired client relationships-mutual fund management contracts |  |  |  |
Indefinite-lived |  |  |  |
Amortization and Impairment |  |  | (102.2) |
Net book value balance at the end of the period | 38.2 |  | 38.2 |
Indefinite-lived intangible assets fair value assumptions, weighted average annual growth rate (as a percent) |  |  | 10.00% |
Indefinite-lived intangible assets fair value assumptions, discount rate (as a percent) |  |  | 15.00% |
Acquired client relationships |  |  |  |
Definite-lived |  |  |  |
Gross book value balance at the beginning of the period |  |  | 970.5 |
Accumulated amortization balance at the beginning of the period |  |  | (317.0) |
Net book value balance at the beginning of the period |  |  | 653.5 |
New investments |  |  | 131.1 |
Amortization and impairment |  |  | (66.9) |
Foreign currency translation |  |  | 1.3 |
Transfer |  |  | 38.2 |
Gross book value balance at the end of the period | 1,141.1 |  | 1,141.1 |
Accumulated amortization balance at the end of the period | (383.9) |  | (383.9) |
Net book value balance at the end of the period | 757.2 |  | 757.2 |
Amortization expenses |  |  |  |
Weighted average life |  |  | 11 years |
Annual amortization expense for the next five years |  |  | 95.0 |
Number of annual periods of expected amortization expense |  |  | 5 years |
Amortization expense during the period | 24.0 | 22.1 | 66.9 | 66.3
Acquired client relationships under equity method investments |  |  |  |
Amortization expenses |  |  |  |
Weighted average life |  |  | 8 years |
Amortization expense during the period | $ 10.2 | $ 8.2 | $ 26.5 | $ 24.8

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