Future Interest Agreement - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended		1 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 Scenario, Forecast	Mar. 31, 2003 The 2003 Agreement
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt agreement			The terms of the 2003 Agreement provided that NPAEP and PVPG: (a) reduce to 4.1% per year the annual interest rate payable on any NPAEP Wrap Note or PVPG Wrap Note that bears a stated annual interest rate in excess of that amount (the reduction in the interest rate was evaluated by NPAMLP in accordance with FASB authoritative guidance, and was determined not to be a substantial modification of terms as defined therein); (b) remove certain of the properties secured by the NPAEP and PVPG Wrap Mortgages from the burden of the cross-default and cross-collateralization provisions currently contemplated by the Restructuring Agreement effective as of January 1, 1990 by and among MLPG, NPAMLP, National Property Analysts, Inc. and others; and (c) agree to release the lien of the Wrap Mortgages from the Properties upon a sale of or the agreement of a leasehold estate in any Property prior to the maturity of the applicable Wrap Note. In consideration for the above, NPAMLP modified the NPAEP Wrap Mortgages and the PVPG Wrap Mortgages to provide that (i) there is an event of default under the applicable NPAEP Wrap Mortgages or PVPG Wrap Mortgages, as the case may be, if a judgment or other lien is entered against the title or lease-holding entity thereby entitling NPAEP or PVPG, as the case may be, to avail itself of the post-default rights or remedies under the relevant security document; and (ii) for cross-default and cross-collateralization among certain partnerships comprising NPAMLP. In addition NPAMLP shall execute and deliver to NPAEP or PVPG, as the case may be, a currently recordable deed of future interest (or assignment of future leasehold interest) sufficient to convey to NPAEP or PVPG, as the case may be, all of NPAMLP’s right, title, interest and estate in and to its fee or leasehold interest in the encumbered properties effective upon the maturity on December 31, 2013 of the NPAEP Wrap Mortgages and the PVPG Wrap Mortgages unless the Wrap Mortgages have previously been paid in full
Annual interest rate payable on any NPAEP Wrap Note or PVPG Wrap Note			4.10%
Effective date of agreement between NPAMLP, NPAEP and Penn Valley Pension Group ("PVPG")			January 1, 2003
Projected balance due for all of the Wrap Mortgages at December 31, 2013		$ 108,000
2012 Remainder mortgage principal requirements	$ 1,894