Investments in Marketable Securities (Held to Maturity Securities, by Maturity) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities	$ 108,000	$ 107,000
Letters of Credit Outstanding, Amount		1,400,000
Held-to-maturity Securities, Current	522,000	534,000
Held-to-maturity Securities, Noncurrent	1,070,000	1,057,000
Held-to-maturity Securities, Total	1,592,000	1,591,000
Mutual Funds [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities	60,000	59,000
Cash/Money Market Accounts [Member]
Schedule of Held-to-maturity Securities [Line Items]
Available-for-sale Securities	48,000	48,000
Held-to-maturity Securities, Current	98,000	204,000
Held-to-maturity Securities, Noncurrent	0	0
Held-to-maturity Securities, Total	98,000	204,000
US Treasury Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Current	295,000	105,000
Held-to-maturity Securities, Noncurrent	940,000	965,000
Held-to-maturity Securities, Total	1,235,000	1,070,000
US Government Agencies Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Current	129,000	225,000
Held-to-maturity Securities, Noncurrent	130,000	92,000
Held-to-maturity Securities, Total	$ 259,000	$ 317,000