Investments in Mortgage Revenue Bonds - Description of Certain Terms of Partnership's MRBs (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Summary Of Investment Holdings [Line Items]
Principal Outstanding		$ 719,750,361		$ 648,439,860
15 West Apartments [Member] | Series A [Member] | Vancouver, Washington [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016	[2]
Maturity Date		Jul. 01, 2054	[1]	Jul. 01, 2054	[2]
Base Interest Rate		6.25%	[1]	6.25%	[2]
Principal Outstanding		$ 9,797,833	[1]	$ 9,850,000	[2]
Arbors at Hickory Ridge [Member] | Memphis, Tennessee [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2012	[3]	2012	[4]
Maturity Date		Jan. 01, 2049	[3]	Jan. 01, 2049	[4]
Base Interest Rate		6.25%	[3]	6.25%	[4]
Principal Outstanding		$ 11,237,041	[3]	$ 11,351,321	[4]
Avistar at Copperfield [Member] | Series A [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[1]	2017
Maturity Date	[1]	May 01, 2054
Base Interest Rate	[1]	5.75%
Principal Outstanding	[1]	$ 10,000,000
Avistar at Copperfield [Member] | Series B [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jun. 01, 2054
Base Interest Rate		12.00%
Principal Outstanding		$ 4,000,000
Avistar on the Boulevard [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[3]	2013
Maturity Date	[3]	Mar. 01, 2050
Base Interest Rate	[3]	6.00%
Principal Outstanding	[3]	$ 16,109,972
Avistar at the Crest [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Mar. 01, 2050	[3]	Mar. 01, 2050	[4]
Base Interest Rate		6.00%	[3]	6.00%	[4]
Principal Outstanding		$ 9,456,384	[3]	$ 9,549,644	[4]
Avistar (February 2013 Acquisition) [Member] | Series B [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013		2013
Maturity Date		Apr. 01, 2050		Apr. 01, 2050
Base Interest Rate		9.00%		9.00%
Principal Outstanding		$ 1,194,783		$ 2,158,382
Avistar at the Oaks [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Aug. 01, 2050	[3]	Aug. 01, 2050	[4]
Base Interest Rate		6.00%	[3]	6.00%	[4]
Principal Outstanding		$ 7,635,895	[3]	$ 7,709,040	[4]
Avistar in 09 [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Aug. 01, 2050	[3]	Aug. 01, 2050	[4]
Base Interest Rate		6.00%	[3]	6.00%	[4]
Principal Outstanding		$ 6,593,300	[3]	$ 6,656,458	[4]
Avistar on the Hills [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Aug. 01, 2050	[3]	Aug. 01, 2050	[4]
Base Interest Rate		6.00%	[3]	6.00%	[4]
Principal Outstanding		$ 5,275,623	[3]	$ 5,326,157	[4]
Avistar (June 2013 Acquisition) [Member] | Series B [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013		2013
Maturity Date		Sep. 01, 2050		Sep. 01, 2050
Base Interest Rate		9.00%		9.00%
Principal Outstanding		$ 1,000,419		$ 1,005,226
Avistar at the Parkway [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2015		2015
Maturity Date	[5]	May 01, 2052		May 01, 2052
Base Interest Rate	[5]	6.00%		6.00%
Principal Outstanding	[5]	$ 13,233,665		$ 13,300,000
Avistar at the Parkway [Member] | Series B [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015		2015
Maturity Date		Jun. 01, 2052		Jun. 01, 2052
Base Interest Rate		12.00%		12.00%
Principal Outstanding		$ 124,861		$ 125,000
Avistar at Wilcrest [Member] | Series A [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[1]	2017
Maturity Date	[1]	May 01, 2054
Base Interest Rate	[1]	5.75%
Principal Outstanding	[1]	$ 3,775,000
Avistar at Wilcrest [Member] | Series B [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jun. 01, 2054
Base Interest Rate		12.00%
Principal Outstanding		$ 1,550,000
Bella Vista [Member] | Gainesville, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2006		2006
Maturity Date	[6]	Apr. 01, 2046		Apr. 01, 2046
Base Interest Rate	[6]	6.15%		6.15%
Principal Outstanding	[6]	$ 6,295,000		$ 6,365,000
Bridle Ridge [Member] | Greer South Carolina
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2008		2008
Maturity Date	[6]	Jan. 01, 2043		Jan. 01, 2043
Base Interest Rate	[6]	6.00%		6.00%
Principal Outstanding	[6]	$ 7,465,000		$ 7,535,000
Avistar at Wood Hollow [Member] | Series A [Member] | Austin, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[1]	2017
Maturity Date	[1]	May 01, 2054
Base Interest Rate	[1]	5.75%
Principal Outstanding	[1]	$ 31,850,000
Avistar at Wood Hollow [Member] | Series B [Member] | Austin, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jun. 01, 2054
Base Interest Rate		12.00%
Principal Outstanding		$ 8,410,000
Brookstone [Member] | Waukegan, Illinois [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2009		2009
Maturity Date	[6]	May 01, 2040		May 01, 2040
Base Interest Rate	[6]	5.45%		5.45%
Principal Outstanding	[6]	$ 8,979,174		$ 9,076,558
Bruton [Member] | Dallas, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2014	[1]	2014	[2]
Maturity Date		Aug. 01, 2054	[1]	Aug. 01, 2054	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 18,051,775	[1]	$ 18,145,000	[2]
Columbia Gardens [Member] | Columbia, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Dec. 01, 2050	[1]	Dec. 01, 2050	[2]
Base Interest Rate		5.50%	[1]	5.50%	[2]
Principal Outstanding		$ 13,193,000	[1]	$ 15,000,000	[2]
Companion at Thornhill Apartments [Member] | Lexington, South California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[1]	2016
Maturity Date	[1]	Jan. 01, 2052
Base Interest Rate	[1]	5.80%
Principal Outstanding	[1]	$ 11,404,758
Concord at Gulfgate [Member] | Series A [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Feb. 01, 2032	[1]	Feb. 01, 2032	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 19,185,000	[1]	$ 19,185,000	[2]
Concord at Little York [Member] | Series A [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Feb. 01, 2032	[1]	Feb. 01, 2032	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 13,440,000	[1]	$ 13,440,000	[2]
Concord at Williamcrest [Member] | Series A [Member] | Houston, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Feb. 01, 2032	[1]	Feb. 01, 2032	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 20,820,000	[1]	$ 20,820,000	[2]
Courtyard Apartments [Member] | Series A [Member] | Fullerton California
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2033	[1]	Dec. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 10,230,000	[1]	$ 10,230,000
Courtyard Apartments [Member] | Series B [Member] | Fullerton California
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2018	[1]	Dec. 01, 2018
Base Interest Rate		8.00%	[1]	5.50%
Principal Outstanding		$ 6,228,000	[1]	$ 6,228,000
Cross Creek [Member] | Beaufort, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2009		2009
Maturity Date	[6]	Mar. 01, 2049		Mar. 01, 2049
Base Interest Rate	[6]	6.15%		6.15%
Principal Outstanding	[6]	$ 8,168,529		$ 8,258,605
Crossing at 1415 [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Dec. 01, 2052	[1]	Dec. 01, 2052	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 7,540,000	[1]	$ 7,590,000	[2]
Crossing at 1415 [Member] | Series B [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired				2015
Maturity Date				Jan. 01, 2053
Base Interest Rate				12.00%
Principal Outstanding				$ 335,000
Decatur Angle [Member] | Fort Worth, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2014	[1]	2014	[2]
Maturity Date		Jan. 01, 2054	[1]	Jan. 01, 2054	[2]
Base Interest Rate		5.75%	[1]	5.75%	[2]
Principal Outstanding		$ 22,794,912	[1]	$ 22,950,214	[2]
Glenview [Member] | Series A [Member] | Cameron, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2014		2014
Maturity Date	[5]	Dec. 01, 2031		Dec. 01, 2031
Base Interest Rate	[5]	5.75%		5.75%
Principal Outstanding	[5]	$ 4,627,228		$ 4,670,000
Greens of Pine Glen [Member] | Series A [Member] | Durham North Carolina
Summary Of Investment Holdings [Line Items]
Year Acquired		2012	[3]	2012	[4]
Maturity Date		Oct. 01, 2047	[3]	Oct. 01, 2047	[4]
Base Interest Rate		6.50%	[3]	6.50%	[4]
Principal Outstanding		$ 8,126,000	[3]	$ 8,210,000	[4]
Greens of Pine Glen [Member] | Series B [Member] | Durham North Carolina
Summary Of Investment Holdings [Line Items]
Year Acquired		2012		2012
Maturity Date		Oct. 01, 2047		Oct. 01, 2047
Base Interest Rate		9.00%		9.00%
Principal Outstanding		$ 937,399		$ 940,479
Harden Ranch [Member] | Series A [Member] | Salinas, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2014	[3]	2014	[4]
Maturity Date		Mar. 01, 2030	[3]	Mar. 01, 2030	[4]
Base Interest Rate		5.75%	[3]	5.75%	[4]
Principal Outstanding		$ 6,845,985	[3]	$ 6,912,535	[4]
Harmony Court Bakersfield [Member] | Series A [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2033	[1]	Dec. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 3,730,000	[1]	$ 3,730,000
Harmony Court Bakersfield [Member] | Series B [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired				2016
Maturity Date				Dec. 01, 2018
Base Interest Rate				5.50%
Principal Outstanding				$ 1,997,000
Harmony Terrace [Member] | Series A [Member] | Simi Valley, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016	[2]
Maturity Date		Jan. 01, 2034	[1]	Jan. 01, 2034	[2]
Base Interest Rate		5.00%	[1]	5.00%	[2]
Principal Outstanding		$ 6,900,000	[1]	$ 6,900,000	[2]
Harmony Terrace [Member] | Series B [Member] | Simi Valley, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016	[2]
Maturity Date		Jan. 01, 2019	[1]	Jan. 01, 2019	[2]
Base Interest Rate		5.50%	[1]	5.50%	[2]
Principal Outstanding		$ 7,400,000	[1]	$ 7,400,000	[2]
Heights at 515 [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Dec. 01, 2052	[1]	Dec. 01, 2052	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 6,903,000	[1]	$ 6,435,000	[2]
Heights at 515 [Member] | Series B [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired				2015
Maturity Date				Jan. 01, 2053
Base Interest Rate				12.00%
Principal Outstanding				$ 510,000
Heritage Square [Member] | Series A [Member] | Edinburg, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2014		2014
Maturity Date	[5]	Sep. 01, 2051		Sep. 01, 2051
Base Interest Rate	[5]	6.00%		6.00%
Principal Outstanding	[5]	$ 11,063,027		$ 11,161,330
Las Palmas II [Member] | Series A [Member] | Coachella, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Nov. 01, 2033	[1]	Nov. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 1,695,000	[1]	$ 1,695,000
Las Palmas II [Member] | Series B [Member] | Coachella, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Nov. 01, 2018	[1]	Nov. 01, 2018
Base Interest Rate		8.00%	[1]	5.50%
Principal Outstanding		$ 1,770,000	[1]	$ 1,770,000
Montclair [Member] | Series A [Member] | Lemoore, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2014		2014
Maturity Date	[5]	Dec. 01, 2031		Dec. 01, 2031
Base Interest Rate	[5]	5.75%		5.75%
Principal Outstanding	[5]	$ 2,506,828		$ 2,530,000
Oaks at Georgetown [Member] | Series A [Member] | Georgetown, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016	[2]
Maturity Date		Jan. 01, 2034	[1]	Jan. 01, 2034	[2]
Base Interest Rate		5.00%	[1]	5.00%	[2]
Principal Outstanding		$ 12,330,000	[1]	$ 12,330,000	[2]
Oaks at Georgetown [Member] | Series B [Member] | Georgetown, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016	[2]
Maturity Date		Jan. 01, 2019	[1]	Jan. 01, 2019	[2]
Base Interest Rate		5.50%	[1]	5.50%	[2]
Principal Outstanding		$ 5,512,000	[1]	$ 5,512,000	[2]
Montecito at Williams Ranch [Member] | Series A [Member] | Salinas, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Oct. 01, 2034
Base Interest Rate		5.50%
Principal Outstanding		$ 7,690,000
Montecito at Williams Ranch [Member] | Series B [Member] | Salinas, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Oct. 01, 2019
Base Interest Rate		5.50%
Principal Outstanding		$ 4,781,000
Ohio Properties [Member] | Series A [Member] | OH [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2010		2010
Maturity Date	[6]	Jun. 01, 2050		Jun. 01, 2050
Base Interest Rate	[6]	7.00%		7.00%
Principal Outstanding	[6]	$ 14,113,000		$ 14,215,000
Ohio Properties [Member] | Series B [Member] | OH [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2010		2010
Maturity Date		Jun. 01, 2050		Jun. 01, 2050
Base Interest Rate		10.00%		10.00%
Principal Outstanding		$ 3,536,060		$ 3,549,780
Pro Nova 2014-1 [Member] | Knoxville, Tennessee [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2014	[1]	2014	[2]
Maturity Date		May 01, 2034	[1]	May 01, 2034	[2]
Base Interest Rate		6.00%	[1]	6.00%	[2]
Principal Outstanding		$ 10,000,000	[1]	$ 10,000,000	[2]
Rennaisance [Member] | Series A [Member] | Baton Rouge, Louisiana [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2015		2015
Maturity Date	[5]	Jun. 01, 2050		Jun. 01, 2050
Base Interest Rate	[5]	6.00%		6.00%
Principal Outstanding	[5]	$ 11,239,441		$ 11,348,364
Runnymede [Member] | Austin, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2007		2007
Maturity Date	[6]	Oct. 01, 2042		Oct. 01, 2042
Base Interest Rate	[6]	6.00%		6.00%
Principal Outstanding	[6]	$ 10,150,000		$ 10,250,000
Santa Fe [Member] | Series A [Member] | Hesperia, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2014		2014
Maturity Date	[5]	Dec. 01, 2031		Dec. 01, 2031
Base Interest Rate	[5]	5.75%		5.75%
Principal Outstanding	[5]	$ 3,036,928		$ 3,065,000
San Vicente [Member] | Series A [Member] | Soledad, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Nov. 01, 2033	[1]	Nov. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 3,495,000	[1]	$ 3,495,000
San Vicente [Member] | Series B [Member] | Soledad, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Nov. 01, 2018	[1]	Nov. 01, 2018
Base Interest Rate		8.00%	[1]	5.50%
Principal Outstanding		$ 1,825,000	[1]	$ 1,825,000
Rosewood Townhomes [Member] | Series A [Member] | Goose Creek, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jul. 01, 2055
Base Interest Rate		5.75%
Principal Outstanding		$ 9,280,000
Rosewood Townhomes [Member] | Series B [Member] | Goose Creek, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Aug. 01, 2055
Base Interest Rate		12.00%
Principal Outstanding		$ 470,000
Seasons at Simi Valley [Member] | Series A [Member] | Simi Valley, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Sep. 01, 2032	[1]	Sep. 01, 2032	[2]
Base Interest Rate		5.75%	[1]	5.75%	[2]
Principal Outstanding		$ 4,366,195	[1]	$ 4,376,000	[2]
Seasons at Simi Valley [Member] | Series B [Member] | Simi Valley, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015		2015
Maturity Date		Sep. 01, 2018		Sep. 01, 2017
Base Interest Rate		8.00%		8.00%
Principal Outstanding		$ 1,944,000		$ 1,944,000
Seasons Lakewood [Member] | Series A [Member] | Lakewood, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Jan. 01, 2034	[1]	Jan. 01, 2034
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 7,350,000	[1]	$ 7,350,000
Seasons Lakewood [Member] | Series B [Member] | Lakewood, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Jan. 01, 2019	[1]	Jan. 01, 2019
Base Interest Rate		5.50%	[1]	5.50%
Principal Outstanding		$ 5,260,000	[1]	$ 5,260,000
Seasons San Juan Capistrano [Member] | Series A [Member] | San Juan Capistrano, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Jan. 01, 2034	[1]	Jan. 01, 2034
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 12,375,000	[1]	$ 12,375,000
Seasons San Juan Capistrano [Member] | Series B [Member] | San Juan Capistrano, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Jan. 01, 2019	[1]	Jan. 01, 2019
Base Interest Rate		5.50%	[1]	5.50%
Principal Outstanding		$ 6,574,000	[1]	$ 6,574,000
Silver Moon [Member] | Series A [Member] | Albuquerque New Mexico
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2015		2015
Maturity Date	[5]	Aug. 01, 2055		Aug. 01, 2055
Base Interest Rate	[5]	6.00%		6.00%
Principal Outstanding	[5]	$ 7,879,590		$ 7,933,259
Southpark [Member] | Austin, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2009		2009
Maturity Date	[6]	Dec. 01, 2049		Dec. 01, 2049
Base Interest Rate	[6]	6.13%		6.13%
Principal Outstanding	[6]	$ 13,300,000		$ 13,435,000
Summerhill [Member] | Series A [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2033	[1]	Dec. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 6,423,000	[1]	$ 6,423,000
Summerhill [Member] | Series B [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2018	[1]	Dec. 01, 2018
Base Interest Rate		8.00%	[1]	5.50%
Principal Outstanding		$ 3,372,000	[1]	$ 3,372,000
Sycamore Walk [Member] | Series A [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Jan. 01, 2033	[1]	Jan. 01, 2033	[2]
Base Interest Rate		5.25%	[1]	5.25%	[2]
Principal Outstanding		$ 3,632,000	[1]	$ 3,632,000	[2]
Sycamore Walk [Member] | Series B [Member] | Bakersfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2015		2015
Maturity Date		Jan. 01, 2018		Jan. 01, 2018
Base Interest Rate		8.00%		5.50%
Principal Outstanding		$ 1,815,000		$ 1,815,000
South Pointe [Member] | Series A [Member] | Hanahan, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jul. 01, 2055
Base Interest Rate		5.75%
Principal Outstanding		$ 21,600,000
South Pointe [Member] | Series B [Member] | Hanahan, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Aug. 01, 2055
Base Interest Rate		12.00%
Principal Outstanding		$ 1,100,000
The Palms at Premier Park [Member] | Columbia, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[3]	2013
Maturity Date	[3]	Jan. 01, 2050
Base Interest Rate	[3]	6.25%
Principal Outstanding	[3]	$ 19,238,297
Tyler Park Townhomes [Member] | Greenfield California
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Jan. 01, 2030	[3]	Jan. 01, 2030	[4]
Base Interest Rate		5.75%	[3]	5.75%	[4]
Principal Outstanding		$ 5,965,475	[3]	$ 6,024,120	[4]
Vantage at Judson [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]	2015		2015
Maturity Date	[5]	Jan. 01, 2053		Jan. 01, 2053
Base Interest Rate	[5]	6.00%		6.00%
Principal Outstanding	[5]	$ 26,133,557		$ 26,356,498
The Village at Madera [Member] | Series A [Member] | Madera, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2033	[1]	Dec. 01, 2033
Base Interest Rate		5.00%	[1]	5.00%
Principal Outstanding		$ 3,085,000	[1]	$ 3,085,000
The Village at Madera [Member] | Series B [Member] | Madera, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2016	[1]	2016
Maturity Date		Dec. 01, 2018	[1]	Dec. 01, 2018
Base Interest Rate		8.00%	[1]	5.50%
Principal Outstanding		$ 1,719,000	[1]	$ 1,719,000
Westside Village Market [Member] | Shafter, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[3]	2013	[4]
Maturity Date		Jan. 01, 2030	[3]	Jan. 01, 2030	[4]
Base Interest Rate		5.75%	[3]	5.75%	[4]
Principal Outstanding		$ 3,898,427	[3]	$ 3,936,750	[4]
Willow Run [Member] | Columbia, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2015	[1]	2015	[2]
Maturity Date		Dec. 01, 2050	[1]	Dec. 01, 2050	[2]
Base Interest Rate		5.50%	[1]	5.50%	[2]
Principal Outstanding		$ 13,009,000	[1]	$ 15,000,000	[2]
Woodlynn Village [Member] | Maplewood, Minnesota [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2008		2008
Maturity Date	[6]	Nov. 01, 2042		Nov. 01, 2042
Base Interest Rate	[6]	6.00%		6.00%
Principal Outstanding	[6]	$ 4,267,000		$ 4,310,000
Village at River's Edge [Member] | Columbia, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[1]	2017
Maturity Date	[1]	Jun. 01, 2033
Base Interest Rate	[1]	6.00%
Principal Outstanding	[1]	$ 10,000,000
Vineyard Gardens [Member] | Series A [Member] | Oxnard, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jan. 01, 2035
Base Interest Rate		5.50%
Principal Outstanding		$ 3,995,000
Vineyard Gardens [Member] | Series B [Member] | Oxnard, California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2017
Maturity Date		Jan. 01, 2020
Base Interest Rate		5.50%
Principal Outstanding		$ 2,846,000
Ashley Square [Member] | Des Moines, Iowa [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]			1999
Maturity Date	[6]			Dec. 01, 2025
Base Interest Rate	[6]			6.25%
Principal Outstanding	[6]			$ 5,039,000
Avistar on the Boulevard [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[4]			2013
Maturity Date	[4]			Mar. 01, 2050
Base Interest Rate	[4]			6.00%
Principal Outstanding	[4]			$ 16,268,850
Avistar at Chase Hill [Member] | Series A [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[4]			2013
Maturity Date	[4]			Mar. 01, 2050
Base Interest Rate	[4]			6.00%
Principal Outstanding	[4]			$ 9,844,994
Copper Gate Apartments [Member] | Lafayette, Indiana [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired		2013	[5]	2013	[4]
Maturity Date		Dec. 01, 2029	[5]	Dec. 01, 2029	[4]
Base Interest Rate		6.25%	[5]	6.25%	[4]
Principal Outstanding		$ 5,100,000	[5]	$ 5,145,000	[4]
Companion At Thornhill Apts [Member] | Lexington, South California [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[2]			2016
Maturity Date	[2]			Jan. 01, 2052
Base Interest Rate	[2]			5.80%
Principal Outstanding	[2]			$ 11,500,000
Lake Forest Apartments [Member] | Daytona Florida
Summary Of Investment Holdings [Line Items]
Year Acquired	[6]	2001		2001
Maturity Date	[6]	Dec. 01, 2031		Dec. 01, 2031
Base Interest Rate	[6]	6.25%		6.25%
Principal Outstanding	[6]	$ 8,505,000		$ 8,639,000
Live 929 Apartments [Member] | Baltimore Maryland
Summary Of Investment Holdings [Line Items]
Year Acquired		2014	[1]	2014	[2]
Maturity Date		Jul. 01, 2049	[1]	Jul. 01, 2049	[2]
Base Interest Rate		5.78%	[1]	5.78%	[2]
Principal Outstanding		$ 39,995,000	[1]	$ 40,085,000	[2]
The Palms At Premier Park | Columbia, South Carolina [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[4]			2013
Maturity Date	[4]			Jan. 01, 2050
Base Interest Rate	[4]			6.25%
Principal Outstanding	[4]			$ 19,826,716
Vantage at Harlingen [Member] | San Antonio, Texas [Member]
Summary Of Investment Holdings [Line Items]
Year Acquired	[5]			2015
Maturity Date	[5]			Sep. 01, 2053
Base Interest Rate	[5]			6.00%
Principal Outstanding	[5]			$ 24,529,580

[1] Bond held by Deutsche Bank in a secured financing transaction, see Note 17

[2] Bonds held by Deutsche Bank AG in a secured financing transaction, see Note 17

[3] Bonds owned by ATAX TEBS II, LLC (M31 TEBS), see Note 17

[4] Bonds held by ATAX TEBS II, LLC (M31 TEBS), see Note 17

[5] Bonds owned by ATAX TEBS III, LLC (M33 TEBS), see Note 17

[6] Bonds owned by ATAX TEBS I, LLC (M24 TEBS), see Note 17