Stockholders’ Equity - RSU activity (Details)	3 Months Ended
Dec. 31, 2018 $ / shares shares
RSUs
Number of Shares
Balance unvested at the beginning of the period (in shares)	366,460
Granted (in shares)	195,033
Vested (in shares)	(128,949)
Forfeited (in shares)	(15,391)
Balance unvested at the end of the period (in shares)	417,153
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share) \| $ / shares	$ 52.31
Granted (in dollars per share) \| $ / shares	64.33
Vested (in dollars per share) \| $ / shares	50.61
Forfeited (in dollars per share) \| $ / shares	50.04
Balance unvested at the end of the period (in dollars per share) \| $ / shares	$ 58.54
Vested (in shares)	128,949
Performance-based RSUs
Number of Shares
Balance unvested at the beginning of the period (in shares)	635,628
Forfeited (in shares)	(295,759)
Balance unvested at the end of the period (in shares)	339,869
Weighted Average Grant-Date Fair Value
Balance unvested at the beginning of the period (in dollars per share) \| $ / shares	$ 50.11
Forfeited (in dollars per share) \| $ / shares	43.86
Balance unvested at the end of the period (in dollars per share) \| $ / shares	$ 55.54
Performance and market-based RSUs
Number of Shares
Granted (in shares)	219,890
Balance unvested at the end of the period (in shares)	219,890
Weighted Average Grant-Date Fair Value
Granted (in dollars per share) \| $ / shares	$ 67.40
Balance unvested at the end of the period (in dollars per share) \| $ / shares	$ 67.40

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

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 2
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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.

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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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- 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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- Definition

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

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

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-Publisher FASB
-Name Accounting Standards Codification
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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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