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Share-Based Payments (Details 4)
9 Months Ended 12 Months Ended
Jan. 31, 2015
Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Dividend yield 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term in years 1 year 2 months 12 days 1 year 10 months 24 days
Risk-free interest rates 0.60%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
0.40%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Volatility 73.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
95.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term in years 3 years 3 years 8 months 12 days
Risk-free interest rates 1.05%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
1.17%us-gaap_FairValueAssumptionsRiskFreeInterestRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Volatility 100.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
113.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate
/ us-gaap_RangeAxis
= us-gaap_MaximumMember