Commitments and Contingencies - Accrued Exit Charges Reconciliation (Detail) (USD $)	3 Months Ended
	Jul. 31, 2014	Apr. 30, 2014	Jul. 31, 2011
Restructuring and Related Activities [Abstract]
Opening balance	$ 9,016,000	$ 10,465,000	$ 30,884,000
Cash payments, net of estimated sublease income	(1,469,000)	(1,518,000)
Interest accretion	59,000	69,000
Ending balance	$ 7,606,000	$ 9,016,000	$ 30,884,000