Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Operating Loss Carryforwards [Line Items]
Tax Adjustments, Settlements, and Unusual Provisions	$ 56.5	$ 60.1
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	7.9
Unrecognized Tax Benefits, Probability Threshold of Realizing for Tax Benefits Recognition, Minimum Percentage		50.00%
Unrecognized Tax Benefits, Including Foreign Tax Credits and Penalties and Interest	$ 10.4	$ 10.4
Federal statutory tax rate		21.00%	35.00%

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Unrecognized Tax Benefits, Probability Threshold of Realizing for Tax Benefits Recognition, Minimum Percentage

+ References

No definition available.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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