Stock-based Payments - Stock Purchase Warrants Activity (Details) - Warrant [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Beginning Balance	2,109,840	273,055
Number of Shares, Granted	0	1,849,285
Number of Shares, Exercised	0	0
Number of Shares, Forfeited	0	0
Number of Shares, Expired	0	(12,500)
Number of Shares, Ending Balance	2,109,840	2,109,840	273,055
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Exercise Price, Beginning Balance (in usd per share)	$ 5.54	$ 7.32
Weighted Average Exercise Price, Granted (in usd per share)	0.00	5.64
Weighted Average Exercise Price, Exercised (in usd per share)	0.00	0.00
Weighted Average Exercise Price, Forfeited (in usd per share)	0.00	0.00
Weighted Average Exercise Price, Expired (in usd per share)	0.00	0.00
Weighted Average Exercise Price, Ending Balance (in usd per share)	$ 5.54	$ 5.54	$ 7.32
Weighted Average Remaining Contractual Life (Years), Balance	3 years 7 months 12 days	4 years 7 months 6 days	2 years 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Granted	0 years	4 years 10 months 24 days
Aggregate Intrinsic Value, Beginning Balance	$ 3,248	$ 984
Aggregate Intrinsic Value, Granted	0	3,108,000
Aggregate Intrinsic Value, Ending Balance	$ 0	$ 3,248	$ 984