Subsequent Events - Additional Information (Detail) - President and Chief Executive Officer - Scenario, Forecast	3 Months Ended
Jun. 30, 2018 USD ($)
Schedule Of Common Share Purchase [Line Items]
Base salary	$ 750,000
Sign-on bonus	$ 1,600,000
Percentage of annual target bonus	100.00%
Restricted Stock Awards
Schedule Of Common Share Purchase [Line Items]
Value of stock options/awards at grant date	$ 14,750,000
Performance-Based Stock Option
Schedule Of Common Share Purchase [Line Items]
Value of stock options/awards at grant date	$ 1,000,000

Expenditures for salaries of officers. Does not include allocated share-based compensation, pension and post-retirement benefit expense or other labor-related non-salary expense. For commercial and industrial companies, excludes any direct and overhead labor that is included in cost of goods sold.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration