Fair Value Of Financial Instruments (Summary Of Activity Of Level 3 Inputs Measured On A Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Jan. 31, 2015
Fair Value Of Financial Instruments [Abstract]
Balance at April 30, 2014	$ 276
Change in fair value of common stock warrant liability	(130)
Balance at January 31, 2015	$ 146

Amount of gain (loss) recognized on the income statement for financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityGainLossIncludedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration