CONDENSED BALANCE SHEETS [Parenthetical] - $ / shares	Dec. 31, 2017	Mar. 31, 2017	Sep. 04, 1993
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000	20,000,000
Units of limited partnership interest, issued	21,996,102	21,843,147
Units of limited partnership interest, outstanding	21,996,102	21,843,147
Series 15 [Member]
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000
Units of limited partnership interest, issued	3,870,500	3,830,900
Units of limited partnership interest, outstanding	3,870,500	3,830,900
Series 16 [Member]
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000
Units of limited partnership interest, issued	5,429,402	5,392,500
Units of limited partnership interest, outstanding	5,429,402	5,392,500
Series 17 [Member]
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000
Units of limited partnership interest, issued	5,000,000	4,962,947
Units of limited partnership interest, outstanding	5,000,000	4,962,947
Series 18 [Member]
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000
Units of limited partnership interest, issued	3,616,200	3,598,100
Units of limited partnership interest, outstanding	3,616,200	3,598,100
Series 19 [Member]
Beneficial assignee certificate, par value (in dollars per share)	$ 10	$ 10
Units of limited partnership interest, authorized	22,000,000	22,000,000
Units of limited partnership interest, issued	4,080,000	4,058,700
Units of limited partnership interest, outstanding	4,080,000	4,058,700