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Affiliate Equity - Summary of Affiliate Recognized and Unrecognized Expense (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Affiliate Equity [Line Items]
Affiliate equity expense	$ 19.4	$ 16.6
Non-controlling Interests
Affiliate Equity [Line Items]
Non-controlling interests	$ 16.8	12.6
Unrecognized Affiliate Equity Expense [Abstract]
Remaining Life (in years)	6 years		6 years
Non-Controlling Interest	$ 115.5		$ 95.9
Affiliated Entity
Affiliate Equity [Line Items]
Controlling interest	2.6	$ 4.0
Unrecognized Affiliate Equity Expense [Abstract]
Controlling Interest	$ 39.1		$ 33.3
Remaining Life (in years)	5 years		5 years

X

- Definition

Affiliate Equity Compensation Expense, Attributable to Noncontrolling Interest

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No definition available.

+ Details

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X

- Definition

Affiliate Equity Compensation Expense, Including Portion Attributable to Noncontrolling Interest

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No definition available.

+ Details

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- Definition

[Line Items] for Affiliate Equity [Table]

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No definition available.

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- Definition

Affiliate Equity Unrecognized Compensation Expense, Attributable to Noncontrolling Interest

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No definition available.

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- Definition

Affiliate Equity, Unrecognized Compensation Expense, Weighted Average Period of Recognition

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No definition available.

+ Details

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- Definition

Represents the compensation expenses related to Affiliate equity.

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No definition available.

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- Definition

Unrecognized Affiliate Equity Expense [Abstract]

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No definition available.

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- Definition

Unrecognized Compensation Expenses Related to Affiliate Equity Attributable to Controlling Interest

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No definition available.

+ Details

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- Details

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- Details

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