Debt and Financial Instruments - Additional Information (Detail)				3 Months Ended					9 Months Ended
	Sep. 30, 2016 USD ($) MortgageLoan Derivative		Mar. 27, 2015 USD ($) Option	Sep. 30, 2016 USD ($) MortgageLoan Derivative		Jun. 30, 2016 USD ($) Derivative	Mar. 31, 2014 USD ($) Derivative	Sep. 30, 2013 USD ($) Derivative	Sep. 30, 2016 USD ($) MortgageLoan Derivative		May 24, 2016 USD ($)	Dec. 31, 2015 USD ($) MortgageLoan
Debt Instrument [Line Items]
Outstanding borrowings under credit agreement	$ 192,250,000			$ 192,250,000					$ 192,250,000			$ 142,150,000
Outstanding borrowings under letter of credit	2,700,000			2,700,000					2,700,000
Available borrowing capacity	$ 55,000,000			$ 55,000,000					$ 55,000,000
Number of non-recourse mortgages | MortgageLoan	14			14					14			14
Balance of Non Recourse Mortgages	$ 107,849,000	[1]		$ 107,849,000	[1]				$ 107,849,000	[1]		$ 110,300,000
Mortgage and other notes payable, non-recourse to us, debt premium	132,000,000			132,000,000					132,000,000			298,000
Financing fees net	321,000,000			321,000,000					321,000,000			398,000
Mortgage loan fair value	$ 110,000,000			$ 110,000,000					$ 110,000,000			$ 112,000,000
Interest Rate Cap
Debt Instrument [Line Items]
Number of interest rate cap agreements | Derivative	1			1		1	2	1	1
Notional amount	$ 30,000,000			$ 30,000,000		$ 30,000,000	$ 20,000,000	$ 10,000,000	$ 30,000,000
Premium paid				$ 55,000		$ 115,000	$ 134,500	$ 136,000
Expiration date of interest rate cap				Mar. 31, 2019		Mar. 31, 2019	Jan. 31, 2017	Jan. 31, 2017
LIBOR | Interest Rate Cap
Debt Instrument [Line Items]
Derivative instruments, LIBOR rate	1.50%			1.50%		1.50%	1.50%	1.50%	1.50%
Credit Agreement
Debt Instrument [Line Items]
Outstanding borrowing			$ 185,000,000								$ 250,000,000
Unsecured revolving amended credit agreement terminated date			2019-03
Number of additional one year extension options | Option			1
Proceeds from Lines of Credit			$ 50,000,000
Credit facility, Interest Rate Terms									One, two, three, or six month LIBOR plus an applicable margin ranging from 1.50% to 2.00% or at the Base Rate plus an applicable margin ranging from 0.50% to 1.00%.
Base rate description									The greatest of: (a) the administrative agent’s prime rate; (b) the federal funds effective rate plus 1/2 of 1%, and; (c) one month LIBOR plus 1%.
Fee payable on unused portion of commitment	0.25%
Credit Agreement | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate	1.625%
Credit Agreement | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate	0.625%
Credit Agreement | Swingline/Short-Term Loans
Debt Instrument [Line Items]
Outstanding borrowing			20,000,000
Credit Agreement | Letters of Credit
Debt Instrument [Line Items]
Outstanding borrowing			$ 40,000,000
Minimum | Credit Agreement
Debt Instrument [Line Items]
Fee payable on unused portion of commitment			0.20%
Minimum | Credit Agreement | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate			1.50%
Margin points added to the base rate			1.00%
Minimum | Credit Agreement | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate			0.50%
Minimum | Credit Agreement | Federal Funds Effective Rate
Debt Instrument [Line Items]
Margin points added to the base rate			0.50%
Maximum | Credit Agreement
Debt Instrument [Line Items]
Fee payable on unused portion of commitment			0.40%
Maximum | Credit Agreement | LIBOR
Debt Instrument [Line Items]
Margin points added to the reference rate			2.00%
Maximum | Credit Agreement | Base Rate
Debt Instrument [Line Items]
Margin points added to the reference rate			1.00%

[1] All mortgage loans require monthly principal payments through maturity and either fully amortize or include a balloon principal payment upon maturity.