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Equity Method Investments in Affiliates - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2017 | Mar. 31, 2016
Schedule of Equity Method Investments |  |
Amortization expense during the period | $ 21.9 | $ 26.6
Revenue from equity method investments | 265.6 | 206.1
Net income from equity method investments | $ 148.6 | 111.6
Acquired Client Relationships Under Equity Method Investments |  |
Schedule of Equity Method Investments |  |
Weighted average client-acquired relationships | 13 years |
Finite-lived intangible, future amortization expense, next twelve months | $ 80.0 |
Finite-lived intangible, future amortization expense, year 2 | 80.0 |
Finite-lived intangible, future amortization expense, year 3 | 80.0 |
Finite-lived intangible, future amortization expense, year 4 | 80.0 |
Finite-lived intangible, future amortization expense, year 5 | 80.0 |
Affiliated Entity | Acquired Client Relationships Under Equity Method Investments |  |
Schedule of Equity Method Investments |  |
Amortization expense during the period | $ 21.7 | $ 14.2

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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=66902209&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=66006027&loc=d3e16323-109275 + Details
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