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Income Taxes - Changes in Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, valuation allowance	$ 607.8	$ 839.1	$ 768.8
Remeasurement of deferred tax assets	(32.1)	(205.2)	0.0
Release of valuation allowance	0.0	0.0	(6.0)
Expiration of net operating losses	(12.3)	0.0	0.0
Other change in valuation allowance	(11.0)	(26.1)	76.3
Balance, valuation allowance	$ 552.5	$ 607.8	$ 839.1

X

- Definition

Valuation Allowance, Deferred Tax Asset, Expiration of Net Operating Losses

+ References

No definition available.

+ Details

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X

- Definition

Valuation Allowance, Deferred Tax Asset, Release of Valuation Allowance

+ References

No definition available.

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X

- Definition

Valuation Allowance, Deferred Tax Asset, Remeasurement Due To Tax Cuts & Jobs Act

+ References

No definition available.

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X

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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X

- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e32123-109318

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X

- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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