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Summary of Significant Accounting Policies - Concentrations of Credit Risk - Additional Information (Detail)	8 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Apr. 30, 2014	Apr. 30, 2013
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk		As of December 31, 2015 no single group or customer represented greater than 5% of total accounts receivable-trade.
Maximum percentage of accounts receivable represented by single group or customer	100.00%	100.00%	100.00%	100.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Maximum percentage of accounts receivable represented by single group or customer		5.00%

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Summary Of Significant Accounting Policies [Line Items]

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Description of risks that arise due to the volume of business transacted with a particular customer. At a minimum, the description informs financial statement users of the general nature of the risk, but excludes "Information about Major Customers" that may be disclosed elsewhere (for instance, segment disclosures).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6351-108592

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=51801978&loc=d3e6351-108592

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