Subsidiary Guarantors - Schedule of Consolidating Statement of Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (154)	$ (163)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments		(289)
Unrealized gain (loss) resulting from changes in fair value of marketable securities	12
Realized loss (gain) on derivative instruments reclassified into earnings		164
Other comprehensive income (loss), net of tax	12	(125)
Comprehensive income (loss)	(142)	(288)
Less: Comprehensive income (loss) attributable to noncontrolling interests	136	28
Comprehensive income (loss) attributable to common stockholders	(278)	(316)
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(290)	(191)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments
Unrealized gain (loss) resulting from changes in fair value of marketable securities
Realized loss (gain) on derivative instruments reclassified into earnings
Other comprehensive income (loss), net of tax
Comprehensive income (loss)	(290)	(191)
Less: Comprehensive income (loss) attributable to noncontrolling interests
Comprehensive income (loss) attributable to common stockholders	(290)	(191)
Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	9,949	10,143
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments
Unrealized gain (loss) resulting from changes in fair value of marketable securities	12
Realized loss (gain) on derivative instruments reclassified into earnings
Other comprehensive income (loss), net of tax	12
Comprehensive income (loss)	9,961	10,143
Less: Comprehensive income (loss) attributable to noncontrolling interests
Comprehensive income (loss) attributable to common stockholders	9,961	10,143
Non-Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	276	(943)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments		(289)
Unrealized gain (loss) resulting from changes in fair value of marketable securities
Realized loss (gain) on derivative instruments reclassified into earnings		164
Other comprehensive income (loss), net of tax		(125)
Comprehensive income (loss)	276	(1,068)
Less: Comprehensive income (loss) attributable to noncontrolling interests	136	28
Comprehensive income (loss) attributable to common stockholders	140	(1,096)
Elimination [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(10,089)	(9,172)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) resulting from changes in fair value of derivative instruments
Unrealized gain (loss) resulting from changes in fair value of marketable securities
Realized loss (gain) on derivative instruments reclassified into earnings
Other comprehensive income (loss), net of tax
Comprehensive income (loss)	(10,089)	(9,172)
Less: Comprehensive income (loss) attributable to noncontrolling interests
Comprehensive income (loss) attributable to common stockholders	$ (10,089)	$ (9,172)