Schedule IV - Mortgage Loans on Real Estate (Detail) - Mortgage Loans on Real Estate (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Face Amount of Mortgages or Maximum Available Credit	$ 109,250	[1]
Carrying Amount of Mortgages	70,704	[1],[2]
Borrower A [Member] | Mortgages [Member]
Interest Accrual Rates	8.50%
Interest Payment Rates	8.50%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	16,906	[1]
Carrying Amount of Mortgages	16,897	[1],[2]
Borrower B [Member] | Mortgages [Member]
Interest Accrual Rates	8.50%
Interest Payment Rates	8.50%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	23,800	[1]
Carrying Amount of Mortgages	7,016	[1],[2]
Borrower C [Member] | Mortgages [Member]
Interest Accrual Rates	7.00%
Interest Payment Rates	7.00%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	4,358	[1]
Carrying Amount of Mortgages	4,358	[1],[2]
Borrower D [Member] | Mortgages [Member]
Interest Accrual Rates	6.00%
Interest Payment Rates	6.00%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	4,221	[1]
Carrying Amount of Mortgages	4,221	[1],[2]
Borrower E [Member] | Mortgages [Member]
Interest Accrual Rates	8.10%
Interest Payment Rates	8.10%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	13,000	[1]
Carrying Amount of Mortgages	3,835	[1],[2]
Borrower F [Member] | Mortgages [Member]
Interest Accrual Rates	7.57%
Interest Payment Rates	7.57%
Final Maturity Date	Dec. 31, 2019
Face Amount of Mortgages or Maximum Available Credit	6,509	[1]
Carrying Amount of Mortgages	3,792	[1],[2]
Borrower G [Member] | Mortgages [Member]
Interest Accrual Rates	10.00%
Interest Payment Rates	10.00%
Final Maturity Date	Dec. 31, 2033
Face Amount of Mortgages or Maximum Available Credit	3,075	[1]
Carrying Amount of Mortgages	3,075	[1],[2]
Borrower H [Member] | Mortgages [Member]
Interest Accrual Rates	12.00%
Interest Payment Rates	12.00%
Final Maturity Date	Dec. 31, 2016
Face Amount of Mortgages or Maximum Available Credit	5,307	[1]
Carrying Amount of Mortgages	2,706	[1],[2]
Borrower I [Member] | Mortgages [Member]
Interest Accrual Rates	7.57%
Interest Payment Rates	7.57%
Final Maturity Date	Dec. 31, 2019
Face Amount of Mortgages or Maximum Available Credit	4,201	[1]
Carrying Amount of Mortgages	2,633	[1],[2]
Borrower J [Member] | Mortgages [Member]
Interest Accrual Rates	7.57%
Interest Payment Rates	7.57%
Final Maturity Date	Dec. 31, 2019
Face Amount of Mortgages or Maximum Available Credit	3,966	[1]
Carrying Amount of Mortgages	2,584	[1],[2]
Borrower K [Member] | Mortgages [Member]
Interest Accrual Rates	7.57%
Interest Payment Rates	7.57%
Final Maturity Date	Dec. 31, 2019
Face Amount of Mortgages or Maximum Available Credit	3,678	[1]
Carrying Amount of Mortgages	2,394	[1],[2]
Individually Less Than 3% [Member] | Mortgages [Member]
Final Maturity Date	Dec. 31, 2008
Face Amount of Mortgages or Maximum Available Credit	15,779	[1]
Carrying Amount of Mortgages	13,800	[1],[2]
Individually Less Than 3% [Member] | Line of Credit [Member]
Interest Accrual Rates	8.00%
Interest Payment Rates	8.00%
Final Maturity Date	Dec. 31, 2013
Face Amount of Mortgages or Maximum Available Credit	2,400	[1]
Carrying Amount of Mortgages	1,405	[1],[2]
Capitalized Loan Costs [Member]
Carrying Amount of Mortgages	36
Mortgages [Member]
Face Amount of Mortgages or Maximum Available Credit	104,800	[1]
Carrying Amount of Mortgages	67,311	[1],[2]
Other Loans on Real Estate [Member]
Final Maturity Date	Dec. 31, 2008
Face Amount of Mortgages or Maximum Available Credit	2,050	[1]
Carrying Amount of Mortgages	$ 1,952	[1],[2]

[1] The instruments actual cash flows are denominated in U.S. dollars, Canadian dollars and Mexican pesos as indicated by the geographic location above

[2] The aggregate cost for Federal income tax purposes is $70,704