Annual report pursuant to Section 13 and 15(d)

Investments in Marketable Securities (Details)

v3.3.1.900
Investments in Marketable Securities (Details) - USD ($)
Dec. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities   $ 107,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax $ 13,000 16,000
Letters of credit 1,100,000 1,400,000
Held-to-maturity Securities, Current 388,000 534,000
Held-to-maturity Securities, Noncurrent 905,000 1,057,000
Held-to-maturity Securities 1,293,000 1,591,000
Equity Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities 58,000 59,000
Money Market Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities 48,000 48,000
Held-to-maturity Securities, Current 47,000 204,000
Held-to-maturity Securities, Noncurrent 0 0
Held-to-maturity Securities 47,000 204,000
US Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Held-to-maturity Securities, Current 341,000 105,000
Held-to-maturity Securities, Noncurrent 774,000 965,000
Held-to-maturity Securities 1,115,000 1,070,000
US Government Agencies Debt Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Held-to-maturity Securities, Current 0 225,000
Held-to-maturity Securities, Noncurrent 131,000 92,000
Held-to-maturity Securities $ 131,000 $ 317,000