Stock-Based Compensation - Nonvested Stock Award Activity (Details) $ / shares in Units, $ in Thousands	3 Months Ended
Oct. 31, 2020 USD ($) $ / shares shares
Number of Shares
Nonvested stock awards at the beginning of the period (in shares)	411,715
Granted (in shares)	471,065
Vested (in shares)	(113,239)
Forfeited (in shares)	(6,226)
Nonvested stock awards at the end of the period (in shares)	763,315
Weighted Average Fair Value
Nonvested stock awards at the beginning of the period (in dollars per share) \| $ / shares	$ 76.29
Granted (in dollars per share) \| $ / shares	46.80
Vested (in dollars per share) \| $ / shares	82.34
Forfeited (in dollars per share) \| $ / shares	74.10
Nonvested stock awards at the end of the period (in dollars per share) \| $ / shares	$ 57.53
Aggregate fair value of nonvested stock awards that vested \| $	$ 9,328
Time-based awards
Number of Shares
Nonvested stock awards at the beginning of the period (in shares)	318,702
Granted (in shares)	388,605
Vested (in shares)	(103,819)
Forfeited (in shares)	(5,255)
Nonvested stock awards at the end of the period (in shares)	598,233
Performance-based awards
Number of Shares
Nonvested stock awards at the beginning of the period (in shares)	29,174
Granted (in shares)	(4,455)
Vested (in shares)	(3,037)
Forfeited (in shares)	0
Nonvested stock awards at the end of the period (in shares)	21,682
Market-based awards
Number of Shares
Nonvested stock awards at the beginning of the period (in shares)	63,839
Granted (in shares)	86,915
Vested (in shares)	(6,383)
Forfeited (in shares)	(971)
Nonvested stock awards at the end of the period (in shares)	143,400

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

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)
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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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-Paragraph 2
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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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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).

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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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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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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