Consolidated Statements of Comprehensive Loss (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (154)	$ (163)
Other comprehensive income (loss), net of tax:
Unrealized loss resulting from changes in fair value of derivative instruments		(289)
Realized loss on derivative instruments reclassified into earnings		164
Unrealized gain resulting from changes in fair value of marketable securities	12
Other comprehensive income (loss), net of tax	12	(125)
Comprehensive loss	(142)	(288)
Less: Comprehensive income attributable to noncontrolling interests	136	28
Comprehensive loss attributable to common stockholders	$ (278)	$ (316)