Gross unrealized losses and fair values of investments by investment category and the length of time (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Fair Value	$ 231,000
Less than 12 Months
Fair Value	231,000
Unrealized Loss	(19)
Greater than 12 Months
Fair Value	562,000
Unrealized Loss	(78,000)
Total
Fair Value	793,000
Unrealized Loss	(97,000)
Greater than 12 Months
Fair Value		592,000
Unrealized Loss		(87,000)
Total
Fair Value		592,000
Unrealized Loss		(87,000)
Partnerships owning investments in technology related industries
Fair Value	0
Less than 12 Months
Fair Value	0
Unrealized Loss	0
Greater than 12 Months
Fair Value	358,000
Unrealized Loss	(64,000)
Total
Fair Value	358,000
Unrealized Loss	(64,000)
Less than 12 Months
Fair Value		0
Unrealized Loss		0
Greater than 12 Months
Fair Value		346,000
Unrealized Loss		(76,000)
Total
Fair Value		346,000
Unrealized Loss		(76,000)
Partnerships owning real estate and related investments
Fair Value	0
Less than 12 Months
Fair Value	0
Unrealized Loss	0
Greater than 12 Months
Fair Value	204,000
Unrealized Loss	(14,000)
Total
Fair Value	204,000
Unrealized Loss	(14,000)
Less than 12 Months
Fair Value		0
Unrealized Loss		0
Greater than 12 Months
Fair Value		246,000
Unrealized Loss		(11,000)
Total
Fair Value		246,000
Unrealized Loss		(11,000)
Other investments
Fair Value	231,000
Less than 12 Months
Fair Value	231,000
Unrealized Loss	(19)
Greater than 12 Months
Fair Value	0
Unrealized Loss	0
Total
Fair Value	231,000
Unrealized Loss	(19)
Less than 12 Months
Fair Value		0
Unrealized Loss		0
Greater than 12 Months
Fair Value		0
Unrealized Loss		0
Total
Fair Value		0
Unrealized Loss		$ 0