Stock-Based Compensation - Unrecognized Stock-Based Compensation Expense (Detail) $ in Thousands	Sep. 30, 2018 USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock options	$ 1,906
Non-vested stock awards/stock units	10,343
Performance stock units	3,553
Total	$ 15,802

Employee service share-based compensation not yet recognized, performance stock units

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- References

No definition available.

+ Details

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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

+ Details

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- Definition

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

+ References

+ Details

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- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

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