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Intangible Assets (Details) - USD ($) $ in Millions |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
Jan. 04, 2016 | Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015
Intangible Assets |  |  |  |  |
Amortization and impairment expenses of intangible assets |  | $ 28.6 | $ 28.1 | $ 55.3 | $ 55.9
Acquired Client Relationships |  |  |  |  |
Intangible Assets |  |  |  |  |
Weighted average life |  |  |  | 10 years |
Amortization and impairment expenses of intangible assets |  | 26.7 | 28.1 | $ 53.4 | 55.9
Number of future annual periods of amortization expense (in years) |  |  |  | 5 years |
Annual amortization expense attributable to current equity method Affiliates for next five years |  |  |  |  |
2016 |  | 110.0 |  | $ 110.0 |
2017 |  | 110.0 |  | 110.0 |
2018 |  | 110.0 |  | 110.0 |
2019 |  | 110.0 |  | 110.0 |
2020 |  | 110.0 |  | $ 110.0 |
Acquired Client Relationships | Affiliated Entity |  |  |  |  |
Intangible Assets |  |  |  |  |
Weighted average life |  |  |  | 12 years |
Amortization and impairment expenses of intangible assets |  | 14.8 | $ 8.7 | $ 29.0 | $ 17.5
Annual amortization expense attributable to current equity method Affiliates for next five years |  |  |  |  |
2016 |  | 60.0 |  | 60.0 |
2017 |  | 60.0 |  | 60.0 |
2018 |  | 60.0 |  | 60.0 |
2019 |  | 60.0 |  | 60.0 |
2020 |  | $ 60.0 |  | $ 60.0 |
Systematica Investment LP and Baring Private Equity Asia [Member] | Acquired Client Relationships Under Equity Method Investments |  |  |  |  |
Intangible Assets |  |  |  |  |
Business acquisition, finite-lived intangibles | $ 551.4 |  |  |  |
Baring | Acquired Client Relationships Under Equity Method Investments |  |  |  |  |
Intangible Assets |  |  |  |  |
Business acquisition, goodwill, amortization period for tax deductions (in years) | 15 years |  |  |  |

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- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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- Definition Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275 + Details
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