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Fair Value Disclosures Disclosures related to our financial assets (Details) (Fair Value, Inputs, Level 1 [Member], USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Mar. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale marketable securities $ 21,026 $ 22,227
Municipal Tax Exempt Bond Fund [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale marketable securities 0 22,227
Adjustable Rate Government Fund [Member]
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Available-for-sale marketable securities $ 21,026 $ 0