Investments In and Advances to Partnerships - Advance to Local Partnership and Property Matters (Details) (USD $)	12 Months Ended			12 Months Ended			0 Months Ended		3 Months Ended	12 Months Ended		0 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013	Dec. 31, 2011 Shallowford Oaks [Member]	Dec. 31, 2012 Shallowford Oaks [Member]	Apr. 15, 2010 Shallowford Oaks [Member]	Dec. 19, 2002 Baltic Plaza [Member]	Dec. 19, 2002 Purchase money note [Member] Baltic Plaza [Member]	Mar. 31, 2013 Purchase money note [Member] Baltic Plaza [Member]	Dec. 31, 2012 Purchase money note [Member] Baltic Plaza [Member]	Dec. 31, 2011 Purchase money note [Member] Baltic Plaza [Member]	Apr. 29, 2013 Affiliate of SP Baltic Plaza, LP [Member] Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Advanced funds, including accrued interest				$ 1,008,738
Advanced funds					0	100,000
Accrued interest receivable				28,390
Loss on foreclosure of Local Partnership	0	31,263		31,263
Cash proceeds from sale							2,053,358
Purchase money note term (in years)								30 years
Principal amount								2,300,000		2,300,000	2,300,000
Interest rate									4.60%
Minimum annual payment, percent of marker/purchaser's annual audited cash flow									50.00%
Payments of principal or interest received										0	0
Beneficial interest in purchase money note									98.00%	98.00%	98.00%
Discounted original principal balance plus estimated accrued interest									619,000	619,000	619,000
Note Receivable, Sale Price			2,000,000
Proceeds from Sale of Notes Receivable												$ 1,960,000