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Statement of Changes in Stockholders' Equity (Parenthetical)
7 Months Ended
Dec. 31, 2014
Sale of shares for private placement warrants 7,500,000hdrau_SaleOfSharesForPrivatePlacementWarrants
Common Stock [Member]  
Cancellation of shares 575,000hdrau_StockIssuedDuringPeriodSharesCommonStockCancelled
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Sale of shares for underwriters discount and offering expenses 8,000,000hdrau_SaleOfSharesForUnderwritersDiscountAndOfferingExpenses
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember
Forfeiture of shares due to underwriters not exercising their over-allotment option 300,000hdrau_StockIssuedDuringPeriodSharesCommonStockForfeiture
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonStockMember