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Compensation Plans - Expense Recognition of Deferred Compensation (Detail) - Restricted Stock Units (RSUs)	Mar. 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
2018 (Remaining Period)	$ 5,473,910
2019	6,624,716
2020	4,976,188
2021	3,570,860
2022	2,559,799
Thereafter	702,275
Total	$ 23,907,748

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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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