Quarterly Results (unaudited) (Details) (USD $)	3 Months Ended												12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Quarterly Financial Information [Line Items]
Equity in income of Joint Ventures	$ (4,588)		$ 3,269		$ 79,832		$ 75,814		$ 72,298	$ 59,833	$ 540,268	$ 48,095	$ 154,327	$ 720,494	$ (185,621)
Interest and other income	1,370		1,326		1,785		3,425		3,153	3,870	2,271	1,747	7,906	11,041	2,887
Net income (loss)	(43,513)		(37,700)		37,490		21,656		38,171	27,592	501,846	(14,133)	(22,067)	553,476	(393,956)
Class A Limited Partners
Schedule of Quarterly Financial Information [Line Items]
Net income (loss)													(112,043)	475,159	(483,365)
Net income (loss) allocated to limited partners	(43,078)		(37,323)		(110,819)		79,177		90,493	87,713	221,677	75,276	(112,043)	475,159	(483,365)
Net income (loss) per weighted-average limited partner unit (per unit)	(0.01)		(0.01)		(0.03)		0.02		0.03	0.03	0.07	0.02	(0.03)	0.15	(0.15)
Distribution of operating cash to limited partner (per unit)	0.00		0.00		0.00		0.00		0.00	0.00	0.00	0.00
Distribution of net property sale proceeds to limited partner (per unit)	0.00		0.00		0.99		0.00		0.00	0.00	0.00	0.00
Class B Limited Partners
Schedule of Quarterly Financial Information [Line Items]
Net income (loss)													90,196	77,430	89,409
Net income (loss) allocated to limited partners	0		0		147,934		(57,738)		(52,703)	(60,404)	279,946	(89,409)	90,196	77,430	89,409
Net income (loss) per weighted-average limited partner unit (per unit)	0.00	[1]	0.00	[1]	0.65	[1]	(0.26)	[1]	(0.22)	(0.26)	1.19	(0.38)	0.40	0.33	0.38
Distribution of operating cash to limited partner (per unit)	0.00		0.00		0.00		0.00		0.00	0.00	0.00	0.00
Distribution of net property sale proceeds to limited partner (per unit)	0.00		0.00		1.11		0.00		0.00	0.00	0.00	0.00
General Partners
Schedule of Quarterly Financial Information [Line Items]
Net income (loss)													(220)	887	0
Net income (loss) allocated to general partners	$ (435)		$ (377)		$ 375		$ 217		$ 381	$ 283	$ 223	$ 0	$ (220)	$ 887	$ 0

[1] The quarterly per-unit amounts have been calculated using actual income (loss) for the respective quarters. Conversely, the corresponding annual income (loss) per-unit amounts have been calculated assuming that income (loss) was earned ratably over the year. As a result, the sum of these quarterly per-unit amounts does not equal the respective annual per-unit amount presented in the accompanying financial statements.