Price at closing of a single share of a number of saleable stocks of a company.

No definition available.

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

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No definition available.

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- Definition

Weighted average period over which unrecognized compensation related to stock options 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.

+ References

No definition available.

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- Definition

Period from grant date that an share-based payments award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment awards number of units eligible to vest as a multiple of number of units granted.

+ References

No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29)
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
-Subparagraph (i)
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- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

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- Definition

Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2A
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- Definition

Amount of cash inflow from exercise of stock options granted under share-based compensation arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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-Paragraph 2
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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 maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

Number of share instruments newly issued under a share-based compensation plan.

+ References

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ References

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- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Share-Based Compensation - Textual (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) shares	Apr. 26, 2017 shares
Share-based Compensation Plans (Textual)
Share-based compensation expense	$ 1.7	$ 3.8
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	1.4	6.1
Cash received from option exercises	$ 0.9	0.9
Stock Incentive Plan of 2015
Share-based Compensation Plans (Textual)
Common stock available for future grants under share-based compensation plans (in shares) \| shares	1,346,965
Stock Incentive Plan of 2017
Share-based Compensation Plans (Textual)
Number of shares authorized under stock incentive plan (in shares) \| shares			1,750,000
Stock Incentive Plans After 2012
Share-based Compensation Plans (Textual)
Vesting period	5 years
Stock Incentive Plans Prior To 2013
Share-based Compensation Plans (Textual)
Vesting period	3 years
Stock options
Share-based Compensation Plans (Textual)
Stock option award vesting period	10 years
Outstanding in-the-money stock options, intrinsic value		$ 29.0
Stock issued from exercises (in shares) \| shares	100,885	496,000
Restricted stock units
Share-based Compensation Plans (Textual)
Corporation granted options to purchase restricted stock performance units (in shares) \| shares	275,355
Stock issued from exercises (in shares) \| shares	61,342
Unrecognized compensation expense	$ 21.9
Unrecognized compensation expense, period for recognition	3 years 7 months
Restricted stock units \| Minimum
Share-based Compensation Plans (Textual)
Restricted stock performance units eligible to vest as a multiple of number of units granted	0.5
Restricted stock units \| Maximum
Share-based Compensation Plans (Textual)
Restricted stock performance units eligible to vest as a multiple of number of units granted	1.5
Equity Option
Share-based Compensation Plans (Textual)
Weighted-average remaining contractual terms for outstanding stock options	6 years 6 months
Weighted-average remaining contractual terms for exercisable stock options	5 years 11 months
Outstanding in-the-money stock options, intrinsic value	$ 21.5
Exercisable in-the-money stock options, intrinsic value	$ 17.3
Closing price of common stock (dollars per share) \| $ / shares	$ 54.68
Unrecognized compensation expense	$ 1.8
Unrecognized compensation expense, period for recognition	3 years 3 months
Restricted stock awards
Share-based Compensation Plans (Textual)
Unrecognized compensation expense	$ 1.7
Unrecognized compensation expense, period for recognition	10 months 15 days