Long-Term Debt (Narrative) (Details) (USD $)	3 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Apr. 30, 2012
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ (2,166,000)
Revolving credit agreement, amount	8,000,000
Term loan amount	19,453,000		21,251,000
Reference rate	LIBOR
Basis spread on variable reference rate	5.00%
Stated interest rate, minimum	6.50%
Line of Credit Facility, Amount Outstanding	5,500,000
Term Note A [Member]
Debt Instrument [Line Items]
Term loan amount	9,400,000	12,000,000	11,100,000
Reference rate	LIBOR
Basis spread on variable reference rate	5.00%	5.00%
Stated interest rate, minimum	6.50%	1.50%
Term Note B [Member]
Debt Instrument [Line Items]
Term loan amount	4,000,000	4,000,000	4,000,000
Reference rate	LIBOR
Basis spread on variable reference rate	10.00%	10.00%
Stated interest rate, minimum	12.00%	2.00%
Wells Fargo Revolving Line Of Credit [Member]
Debt Instrument [Line Items]
Loan costs related to agreement		600,000
Revolving credit agreement, amount		8,000,000
Term loan amount	5,500,000		5,500,000
Reference rate	LIBOR
Basis spread on variable reference rate	5.00%	5.00%
Stated interest rate, minimum	6.50%
Hercules Term Loan and Credit Facility [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt		2,200,000
Unamortized loan costs		1,000,000
Warrant discounts		800,000
Prepayment fees		$ 400,000