Investment in Other Joint Ventures - Balance Sheet Information (Details) (Research Triangle Industrial Park Joint Venture, USD $)	Jun. 30, 2012	Dec. 31, 2011
Research Triangle Industrial Park Joint Venture
Assets:
Cash and equivalents	$ 41,243	$ 488,152
Receivable from affiliates	1,753,222	1,524,869
Accrued interest receivable from affiliates	464,773	422,521
Total assets	2,259,238	2,435,542
Liabilities:
Accounts payable and accrued expenses
Payable to affiliates		218,322
Total liabilities		218,322
The Partnership	1,129,619	1,108,610
RPILP - VI A	1,129,619	1,108,610
Total partners' equity	2,259,238	2,217,220
Total liabilities and partners' equity	$ 2,259,238	$ 2,435,542