Annual report pursuant to Section 13 and 15(d)

Investments in Marketable Securities (Details)

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Investments in Marketable Securities (Details) (USD $)
Dec. 31, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities $ 92,000 $ 127,000
Available-for-sale Securities, Gross Unrealized Gains 11,000 12,000
Letters of Credit Outstanding, Amount 2,600,000 3,100,000
Held-to-maturity Securities, Current 2,008,000 1,434,000
Held-to-maturity Securities, Noncurrent 1,788,000 3,841,000
Held-to-maturity Securities 3,796,000 5,275,000
Equity Funds [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities 44,000 65,000
Money Market Funds [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities 48,000 62,000
Held-to-maturity Securities, Current 76,000 111,000
Held-to-maturity Securities, Noncurrent 0 0
Held-to-maturity Securities 76,000 111,000
US Treasury Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Held-to-maturity Securities, Current 1,051,000 1,323,000
Held-to-maturity Securities, Noncurrent 1,399,000 2,970,000
Held-to-maturity Securities 2,450,000 4,293,000
US Government Agencies Debt Securities [Member]
   
Schedule of Available-for-sale Securities [Line Items]    
Held-to-maturity Securities, Current 881,000 0
Held-to-maturity Securities, Noncurrent 389,000 871,000
Held-to-maturity Securities $ 1,270,000 $ 871,000