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Compensation Plans - Expense Recognition of Deferred Compensation (Detail) - Restricted Stock Units (RSUs)	Sep. 30, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2018 (Remaining Period)	$ 1,850,410
2019	6,863,879
2020	5,399,940
2021	4,087,381
2022	3,100,248
Thereafter	1,200,348
Total	$ 22,502,206

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Unrecognized cost of unvested share-based compensation awards.

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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

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