Quarterly report pursuant to Section 13 or 15(d)

Investments in Marketable Securities (Held to Maturity Securities, by Maturity) (Details)

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Investments in Marketable Securities (Held to Maturity Securities, by Maturity) (Details) (USD $)
Jun. 30, 2012
Dec. 31, 2011
Schedule of Held-to-maturity Securities [Line Items]    
Available-for-sale Securities $ 91,000 $ 127,000
Letters of Credit Outstanding, Amount 2,900,000 3,100,000
Held-to-maturity Securities, Current 1,927,000 1,434,000
Held-to-maturity Securities, Noncurrent 3,329,000 3,841,000
Held-to-maturity Securities, Total 5,256,000 5,275,000
Mutual Funds [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Available-for-sale Securities 43,000 65,000
Cash/Money Market Accounts [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Available-for-sale Securities 48,000 62,000
Held-to-maturity Securities, Current 167,000 111,000
Held-to-maturity Securities, Noncurrent 0 0
Held-to-maturity Securities, Total 167,000 111,000
US Treasury Securities [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity Securities, Current 1,321,000 1,323,000
Held-to-maturity Securities, Noncurrent 2,484,000 2,970,000
Held-to-maturity Securities, Total 3,805,000 4,293,000
US Government Agencies Securities [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity Securities, Current 439,000 0
Held-to-maturity Securities, Noncurrent 845,000 871,000
Held-to-maturity Securities, Total $ 1,284,000 $ 871,000