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Affiliate Equity - Summary of Affiliate Recognized and Unrecognized Expense (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Affiliate Equity [Line Items] |  |  |  |  |
Affiliate equity expense | $ 16.0 | $ 10.0 | $ 43.7 | $ 38.6 |
Non- controlling Interests |  |  |  |  |
Affiliate Equity [Line Items] |  |  |  |  |
Non-controlling interests | 9.9 | 7.7 | $ 32.8 | 29.2 |
Unrecognized Affiliate Equity Expense [Abstract] |  |  |  |  |
Remaining Life (in years) |  |  | 6 years |  | 6 years
Non-Controlling Interest |  |  | $ 120.0 |  | $ 95.9
Affiliated Entity |  |  |  |  |
Affiliate Equity [Line Items] |  |  |  |  |
Controlling interest | $ 6.1 | $ 2.3 | 10.9 | $ 9.4 |
Unrecognized Affiliate Equity Expense [Abstract] |  |  |  |  |
Controlling Interest |  |  | $ 36.8 |  | $ 33.3
Remaining Life (in years) |  |  | 5 years |  | 5 years

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- Definition Affiliate Equity Compensation Expense, Attributable to Noncontrolling Interest + References No definition available. + Details
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- Definition Affiliate Equity Compensation Expense, Including Portion Attributable to Noncontrolling Interest + References No definition available. + Details
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- Definition [Line Items] for Affiliate Equity [Table] + References No definition available. + Details
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- Definition Affiliate Equity Unrecognized Compensation Expense, Attributable to Noncontrolling Interest + References No definition available. + Details
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- Definition Affiliate Equity, Unrecognized Compensation Expense, Weighted Average Period of Recognition + References No definition available. + Details
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- Definition Represents the compensation expenses related to Affiliate equity. + References No definition available. + Details
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- Definition Unrecognized Affiliate Equity Expense [Abstract] + References No definition available. + Details
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- Definition Unrecognized Compensation Expenses Related to Affiliate Equity Attributable to Controlling Interest + References No definition available. + Details
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- Details
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- Details
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