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Goodwill and Acquired Client Relationships - Schedule of Changes in, and the Components of, Acquired Client Relationships (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Net Book Value |  |  |
Net book value balance at the beginning of the period | $ 1,686.4 |  |
Intangible amortization and impairments | (110.2) | $ (115.4) | $ (122.2)
Net book value balance at the end of the period | 1,497.4 | 1,686.4 |
Customer Relationships |  |  |
Definite-lived |  |  |
Gross book value, balance at the beginning of the period | 1,301.8 | 1,255.1 |
Accumulated amortization, balance at the beginning of the period | (680.4) | (565.0) |
Net book value, balance at the beginning of the period | 621.4 | 690.1 |
New Investments | 0.0 | 52.5 |
Intangible amortization and impairments | (107.7) | (115.4) |
Foreign currency translation | (11.8) | (5.8) |
Gross book value, balance at the end of the period | 1,290.0 | 1,301.8 | 1,255.1
Accumulated amortization, balance at the end of the period | (788.1) | (680.4) | (565.0)
Net book value, balance at the end of the period | 501.9 | 621.4 | 690.1
Indefinite-lived |  |  |
Net book value, balance at the beginning of the period | 1,065.0 | 1,088.3 |
New investments | 0.0 | 0.0 |
Impairment | (2.5) | 0.0 |
Foreign currency translation | (67.0) | (23.3) |
Net book value, balance at the end of the period | 995.5 | 1,065.0 | 1,088.3
Net Book Value |  |  |
Net book value balance at the beginning of the period | 1,686.4 | 1,778.4 |
New investments | 0.0 | 52.5 |
Intangible amortization and impairments | (110.2) | (115.4) |
Foreign currency translation | (78.8) | (29.1) |
Net book value balance at the end of the period | $ 1,497.4 | $ 1,686.4 | $ 1,778.4

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