Represents the payout percentage based upon the performance during the performance period.

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

+ Details

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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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.

+ Details

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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- Details

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- Details

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Share-Based Compensation Plans - Executive Performance Incentive Programs - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award requisite service period	36 months
Performance Shares \| 2016 Executive Performance Incentive Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs on non-vested awards	$ 12.9
Performance Shares \| 2017 Executive Performance Incentive Program, Equity
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs on non-vested awards	6.4
Performance Shares \| 2017 Executive Performance Incentive Program, Liability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs on non-vested awards	$ 7.9
Performance Share, Equity Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	3 years	3 years	3 years	3 years	3 years
Performance Shares, Liability Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	2 years
Minimum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation plan, award as a percentage of target award level	0.00%
Maximum \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation plan, award as a percentage of target award level	300.00%