Supplemental Balance Sheets and Statements of Operations Detail (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Accounts receivable:
Trade	$ 123,607	$ 112,292
Allowance for doubtful accounts	(1,401)	(1,255)
Ship-from-stock and debit	(18,041)	(14,116)
Returns	(2,993)	(1,421)
Rebates	(1,035)	(1,071)
Price protection	(125)	(376)
Other	(1,065)	(279)
Accounts receivable	98,947	93,774
Inventories:
Raw materials and supplies	90,968	84,149
Work in process	61,310	64,498
Finished goods	62,522	68,705
Inventories, gross	214,800	217,352
Inventory reserves	(26,826)	(18,464)
Inventories, net	187,974	198,888
Allowance for commitments related to accounts receivables
Changes in allowance for accounts receivable and inventory reserve
Balance at the beginning of the period	18,518	17,463	17,335
Charged to operations	89,909	82,738	71,462
Write-offs	(83,911)	(81,621)	(71,237)
Other	144	(62)	(97)
Balance at the end of the period	24,660	18,518	17,463
Inventory reserves
Changes in allowance for accounts receivable and inventory reserve
Balance at the beginning of the period	18,464	17,144	15,464
Costs charged to expense	10,638	3,145	9,941
Write-offs	(2,672)	(1,488)	(8,253)
Other	396	(337)	(8)
Balance at the end of the period	$ 26,826	$ 18,464	$ 17,144