Mortgages - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended					6 Months Ended		1 Months Ended		6 Months Ended	12 Months Ended		1 Months Ended			6 Months Ended
Mortgages - Additional Information (Detail) (USD $)	Dec. 31, 2006	Jun. 30, 2013	Dec. 31, 2006	Dec. 31, 2004	Dec. 31, 1999	Dec. 31, 2012	Oct. 15, 2009	Jun. 30, 2013 Line of Credit [Member]	Oct. 15, 2009 Line of Credit [Member]	Jan. 31, 2012 Line of Credit [Member] Minimum [Member]	Dec. 29, 2004 First Mortgage [Member]	Jun. 30, 2013 First Mortgage [Member]	Dec. 31, 2005 First Mortgage [Member]	Jan. 05, 2007 First Mortgage [Member]	Sep. 01, 2005 Pre-Existing First Mortgage [Member]	Mar. 05, 2009 Second Mortgage [Member]	May 25, 2006 Second Mortgage [Member]	Jun. 30, 2013 Second Mortgage [Member]
Debt Instrument [Line Items]
Debt instrument amount							$ 42,910,000		$ 21,000,000		$ 30,500,000						$ 12,410,000
Repayments of debt											3,000,000		27,500,000		15,500,000	10,310,000	2,100,000
Debt instrument interest rate														5.33%		6.13%
Loan, monthly payments												184,213						80,947
Term of mortgage												25 years						25 years
Loan, balance amount												26,036,875						11,389,898
Principal amount on maturity date												24,680,713						10,936,920
Debt maturity date												Jan. 05, 2015						Jan. 05, 2015
Maximum period for no prepayment penalty at the end of term												60 days						60 days
Debt instrument outstanding		14,934,616					934,616
Debt instrument additional balance		14,000,000
Interest rate basis points								5.00% or (ii) 300 basis points in excess of the weekly average yield on U .S. Treasury Securities adjusted to a maturity date closest to the mortgage maturity date
Previous floor rate on line of credit		6.50%
Floor rate on line of credit		4.25%
Interest rate under condition first for fixed rate calculation										4.75%
Basis points in addition to weekly average yield under second condition for fixed rate calculation		3.00%
Modified fixed interest rate for prepayment without prepayment fees		5.00%
Fair value of mortgage debt		54,526,767
Increase in building improvement program costs	82,300,000		82,300,000	31,400,000	12,200,000
Previous debt instrument maximum amount		42,910,000
Debt instrument maximum amount		63,900,000
Actual improvement costs		54,386,429
Additional borrowing available from line of credit		21,000,000
Payable to Lessee, a related party		$ 6,767,038				$ 3,322,181

250 WEST 57TH ST ASSOCIATES L.L.C. 10-Q