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Fair Value Measurements and Marketable Securities - Additional Information (Detail) (USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Fair Value Measurements [Line Items]        
Unrealized loss from marketable securities $ 26,000 $ 107,000 $ 82,000 $ 252,000
Proceeds from sales of available for sale of municipal bonds 4,274,000 1,123,000 14,871,000 2,626,000
Realized gains recorded in other income, investment and interest caption 41,000   224,000 2,000
Realized losses recorded in other income, investment and interest caption   $ 1,000