| Note 12 - Commitments and Contingencies (Details Textual) - USD ($) | 12 Months Ended | |
|---|---|---|
| Mar. 29, 2020 | Mar. 31, 2019 | |
| Royalty Expense | $ 4,900,000 | $ 5,200,000 | 
| Royalty Expense Due | 4,200,000 | |
| Royalty Expense Due in Next Twelve Months | 2,600,000 | |
| Royalty Expense Due in Two Years | 1,600,000 | |
| Royalty Expense Due in Three Years | $ 8,000 | |
| X | ||||||||||
| 
- Definition Represents royalty expense due. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Represents royalty expense due in the next twelve months. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Represents royalty expense due in three years. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Represents royalty expense due in two years. No definition available. 
 | 
| X | ||||||||||
| 
- Definition Amount of expense related to royalty payments under a contractual arrangement such as payment for mineral and drilling rights and use of technology or intellectual property. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
 |