Deferred Revenue - Additional information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Jan. 31, 2012 Lease Agreements	Sep. 30, 2012 Lease Agreements	Sep. 30, 2012 Lease Agreements
Deferred Revenue Arrangement [Line Items]
Decrease in wraparound mortgages payable balance due to loan payoffs						$ 4,121
Recognized revenue	2,971	3,008	8,855	9,028			85	255
Deferred revenue balance	$ 4,231		$ 4,231		$ 195		$ 3,866	$ 3,866