Long-Term Debt (Mortgage Notes Payable) - Additional Information (Detail)		1 Months Ended	9 Months Ended
	Apr. 15, 2016 USD ($)	Sep. 30, 2014 USD ($) property	Sep. 30, 2016 USD ($) building property	Mar. 08, 2013 USD ($)	Feb. 22, 2013 USD ($)
UBS Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Note Payable			$ 7,300,000
Wells Fargo Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Note Payable			$ 30,000,000
Mortgage Notes Payable [Member] | UBS Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Note Payable					$ 7,300,000
Maturity period			2018-02
Interest rate on mortgage loan			3.655%
Date of acquisition			Jan. 31, 2013
Mortgage Notes Payable [Member] | UBS Mortgage Note Payable [Member] | Hilton Resorts Corporation [Member]
Debt Instrument [Line Items]
Number of office building | building			2
Mortgage Notes Payable [Member] | BOA Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Note Payable				$ 23,100,000
Interest rate on mortgage loan			3.67%
Number of income properties | property			14
Mortgage Notes Payable [Member] | Wells Fargo Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Note Payable		$ 30,000,000
Maturity period		2034-10
Interest rate on mortgage loan	3.17%	4.33%
Number of income properties | property		6
Mortgage loan payment terms			The mortgage loan matures in October 2034, and carries a fixed rate of 4.33% per annum during the first ten years of the term, and requires payments of interest only during the first ten years of the loan. After the tenth anniversary of the effective date of the loan, the cash flows generated by the underlying six income properties must be used to pay down the principal balance of the loan until paid off or until the loan matures. The loan is fully pre-payable after the tenth anniversary date of the effective date of the loan
Proceeds from first mortgage bond	$ 25,000,000
Term of mortgage loan	5 years
Mortgage loan agreement, description			The mortgage loan has a 5-year term with two years interest only, and interest and a 25-year amortization for the balance of the term
Long-term debt LIBOR plus interest rate, reckoning period	30 days
Line of credit facility, interest rate description			LIBOR plus a rate of 190 basis points
Line of credit facility, basis points added to LIBOR interest rate	1.90%