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Goodwill and Acquired Client Relationships (Details 2) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2012 Y | Jun. 30, 2011 | Jun. 30, 2012 Y | Jun. 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 |  |  | 2.4 |
Transfer |  |  | (38.2) |
Net book value balance at the end of the period | 851.1 |  | 851.1 |
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 |  |  | (145.1) |
Total, Foreign currency translation |  |  | 2.6 |
Total, Net book value balance at the end of the period | 1,631.2 |  | 1,631.2 |
Annual amortization expense attributable to current equity method Affiliates for next five years |  |  |  |
2012 |  |  | 32.7 |
2013 |  |  | 32.7 |
2014 |  |  | 11.2 |
2015 |  |  | 2.7 |
2016 |  |  | 0.2 |
Acquired client relationships-mutual fund management contracts |  |  |  |
Indefinite-lived |  |  |  |
Amortization and Impairment | (93.5) |  | (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 |  |  | (42.9) |
Foreign currency translation |  |  | 0.2 |
Transfer |  |  | 38.2 |
Gross book value balance at the end of the period | 1,140.0 |  | 1,140.0 |
Accumulated amortization balance at the end of the period | (359.9) |  | (359.9) |
Net book value balance at the end of the period | 780.1 |  | 780.1 |
Amortization expenses |  |  |  |
Weighted average life (in years) |  |  | 12 |
Annual amortization expense for the next five years |  |  | 95.0 |
Number of annual periods of expected amortization expense (in years) | 5 |  | 5 |
Amortization expense during the period | 21.2 | 22.1 | 42.9 | 44.2
Acquired client relationships under equity method investments |  |  |  |
Amortization expenses |  |  |  |
Weighted average life (in years) |  |  | 7 |
Number of annual periods of expected amortization expense (in years) | 5 |  | 5 |
Amortization expense during the period | $ 8.2 | $ 8.2 | $ 16.3 | $ 16.6

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