Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Additional share-based compensation cost recognized as a result of an occurrence of an event that accelerates its recognition.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Stock-based Compensation - Additional Disclosures (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Sep. 11, 2017	Sep. 30, 2017	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Surrendered stock options (in shares)			168,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized pre-tax stock-based compensation expense		$ 2.4	$ 2.4
Unrecognized pre-tax stock-based compensation expense, remaining weighted-average life			1 year 9 months 18 days
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized pre-tax stock-based compensation expense		9.8	$ 9.8
Unrecognized pre-tax stock-based compensation expense, remaining weighted-average life			1 year 8 months 12 days
Outside directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Surrendered stock options (in shares)	150,000
Outside directors \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acceleration of stock-based compensation expense		$ 1.2	$ 1.2