Long-Term Debt (Schedule of debt) (detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]
Long-term Debt	$ 218,516	$ 270,186
Total	218,516	270,186
Current Portion of Long-Term Debt	2,277	40,170
Long-Term Debt, Less Current Portion	216,239	230,016
Revolving credit facility [Member]
Debt Instrument [Line Items]
Long-term Debt	175,000	188,000
Long-term Debt, Weighted Average Interest Rate	1.65%	1.70%
Debt Instrument, Maturity Date	2017
Total	175,000	188,000
Secured Note Payable to Insurance Company [Member}
Debt Instrument [Line Items]
Long-term Debt		38,138
Long-term Debt, Weighted Average Interest Rate		8.03%
Debt Instrument, Maturity Date	2014
Total		38,138
Secured Industrial Revenue Development Bonds [Member]
Debt Instrument [Line Items]
Long-term Debt	22,630	22,630
Long-term Debt, Weighted Average Interest Rate	3.23%	3.29%
Debt Instrument, Maturity Date	2029
Total	22,630	22,630
Secured Industrial Revenue Development Bond [Member]
Debt Instrument [Line Items]
Long-term Debt	1,500
Long-term Debt, Weighted Average Interest Rate	2.00%
Debt Instrument, Maturity Date	2021
Total	1,500
Secured promissory note 1 [Member]
Debt Instrument [Line Items]
Long-term Debt	15,313	16,753
Long-term Debt, Weighted Average Interest Rate	6.98%	6.98%
Debt Instrument, Maturity Date	2022
Total	15,313	16,753
Secured promissory note 2 [Member]
Debt Instrument [Line Items]
Long-term Debt	3,731	4,303
Long-term Debt, Weighted Average Interest Rate	6.35%	6.35%
Debt Instrument, Maturity Date	2020
Total	3,731	4,303
Other [Member]
Debt Instrument [Line Items]
Long-term Debt	342	362
Total	$ 342	$ 362

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Carrying amount of long-term debt, net of unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Disclosure of timing of required repayments, sinking fund requirements, and other redeemable securities at fixed or determinable prices and dates in the five years immediately following the date of the latest balance sheet presented in the financial statements, and the amount thereafter to fully repay the principal of long-term debt. These disclosures may be made either on an individual debt or security basis, by type of debt or security basis, or on a combined basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of long-term debt outstanding by type or by instrument at that time.

+ References

No definition available.

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