Note H - Derivative Financial Instruments (Details Textual) xbrli-pure in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Derivative, Gain (Loss) on Derivative, Net, Total	$ 4,000
Derivative, Number of Instruments Held, Total	0	0
Other Current Assets [Member]
Derivative, Collateral, Right to Reclaim Cash	$ 118,125	$ 118,125
Cost of Sales [Member]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 4,000	$ 4,000

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226016-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 8
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
-Paragraph 3
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- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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The number of derivative instruments of a particular group held by the entity.

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-Topic 815
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-Paragraph 1A
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