Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Benefit due to release of valuation allowance on certain foreign deferred tax assets (net operating losses) as a result of indemnification of additional source of taxable income available in prior periods	$ 6.6
Tax benefit due to release of a portion of valuation allowance previously offsetting deferred tax assets associated with existing AMT credit carryforwards		$ 21.1

Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration