Share-Based Payments - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Jul. 19, 2016	Jul. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding, Beginning Balance		2,212,757
Shares, Granted	1,568,191	1,762,327
Shares, Exercised		0
Shares, Forfeited		(7,813)
Shares, Canceled		(1,793,781)
Shares, Expired		(18,542)
Shares, Outstanding, Ending Balance		2,154,948
Shares, Vested and expected to vest		2,154,948
Shares, Exercisable		1,774,069
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Outstanding, Beginning Balance (in usd per share)		$ 5.58
Weighted Average Exercise Price, Granted (in usd per share)	$ 2.10	2.10
Weighted Average Exercise Price, Exercised (in usd per share)		0
Weighted Average Exercise Price, Forfeited (in usd per share)		9.85
Weighted Average Exercise Price, Canceled (in usd per share)		4.92
Weighted Average Exercise Price, Expired (in usd per share)		10.64
Weighted Average Exercise Price, Outstanding, Ending Balance (in usd per share)		3.22
Weighted Average Exercise Price, Vested and expected to vest (in usd per share)		3.22
Weighted Average Exercise Price, Exercisable (in usd per share)		$ 3.35
Weighted Average Remaining Contractual Term, Outstanding, Beginning Balance (in years)		6 years 1 month 6 days
Weighted Average Remaining Contractual Life, Granted (in years)		7 years
Weighted Average Remaining Contractual Term, Outstanding, Ending Balance (in years)		6 years 3 months 18 days
Weighted Average Remaining Contractual Life, Vested and expected to vest (in years)		6 years 3 months 15 days
Weighted Average Remaining Contractual Life, Exercisable (in years)		6 years
Aggregate Intrinsic Value, Outstanding, Beginning Balance		$ 10
Aggregate Intrinsic Value, Granted		0
Aggregate Intrinsic Value, Outstanding, Ending Balance		0
Aggregate Intrinsic Value, Vested and expected to vest		0
Aggregate Intrinsic Value, Exercisable		$ 0
Non-Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding, Beginning Balance		51,250
Shares, Granted		0
Shares, Exercised		0
Shares, Forfeited		0
Shares, Canceled		0
Shares, Expired		0
Shares, Outstanding, Ending Balance		51,250
Shares, Vested and expected to vest		51,250
Shares, Exercisable		34,586
Directors and Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares, Outstanding, Beginning Balance		2,161,507
Shares, Granted		1,762,327
Shares, Exercised		0
Shares, Forfeited		(7,813)
Shares, Canceled		(1,793,781)
Shares, Expired		(18,542)
Shares, Outstanding, Ending Balance		2,103,698
Shares, Vested and expected to vest		2,103,698
Shares, Exercisable		1,739,483