Note 8 - Unrecognized Tax Benefits (Details) (USD $)	9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Apr. 30, 2013
Note 8 - Unrecognized Tax Benefits (Details) [Line Items]
Unrecognized Tax Benefits	$ 11,787,000		$ 8,938,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	7,662,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	432,000		286
Income Tax Examination, Penalties and Interest Expense	146	141
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	$ 1,518
2010 and Forward (Member)
Note 8 - Unrecognized Tax Benefits (Details) [Line Items]
Statute of Limitations for Federal Tax Years Open	2010 and forward
2009 and Forward [Member]
Note 8 - Unrecognized Tax Benefits (Details) [Line Items]
Statute of Limitations for Federal Tax Years Open	2009 and forward