Equity Awards - RSU (Details) - Restricted stock and restricted stock units	9 Months Ended
Sep. 30, 2018 $ / shares shares
Schedule of restricted stock and restricted stock units activity
Beginning Balance, Number of shares or units \| shares	716,128
Grants, Number of shares or units \| shares	154,676
Awards assumed through acquisition of CEC, Number of shares or units \| shares	136,324
Vested shares, Number of shares or units \| shares	(226,371)
Forfeitures, Number of shares or units \| shares	(34,945)
Ending Balance, Number of shares or units \| shares	745,812
Beginning Balance, Weighted-average grant price \| $ / shares	$ 99.65
Awards assumed through acquisition of CEC, Weighted-average grant price \| $ / shares	118.29
Grants, Weighted-average grant price \| $ / shares	92.20
Vested shares, Weighted-average grant price \| $ / shares	75.00
Forfeitures, Weighted-average grant price \| $ / shares	89.13
Ending Balance, Weighted-average grant price \| $ / shares	$ 114.38

Number of share options (or share units) assumed through acquisition during the current period.

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that awarded.

+ References

No definition available.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=109197908&loc=d3e5070-113901

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(3)
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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).

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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-Name Accounting Standards Codification
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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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