Long-Term Debt - Mortgage Notes Payable (Details)	Apr. 15, 2016 USD ($)	Sep. 30, 2014 USD ($) property	Dec. 31, 2016 USD ($)	Sep. 16, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 08, 2013 USD ($) property	Feb. 22, 2013 USD ($) building
UBS Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Notes Payable							$ 7,300,000
Mortgage Notes Payable [Member] | UBS Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Notes Payable			$ 7,300,000		$ 7,300,000
Number of office building | building							2
Interest rate on mortgage loan							3.655%
Mortgage Notes Payable [Member] | BOA Mortgage Note Payable [Member]
Debt Instrument [Line Items]
Mortgage Notes Payable				$ 23,100,000	23,100,000	$ 23,100,000
Number of income properties | property						14
Mortgage Notes Payable [Member] | Wells Fargo Mortgage Note Payable
Debt Instrument [Line Items]
Mortgage Notes Payable		$ 30,000,000	30,000,000		$ 30,000,000
Interest rate on mortgage loan		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, as defined in the related loan agreement, 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.
Mortgage Notes Payable [Member] | Wells Fargo Mortgage Note Payable Two
Debt Instrument [Line Items]
Mortgage Notes Payable	$ 25,000,000		$ 25,000,000
Interest rate on mortgage loan	3.17%
Mortgage loan payment terms	The mortgage loan has a 5-year term, maturing in April 2021, with two years' interest only, and interest and a 25-year amortization for the balance of the term. The mortgage loan bears a variable rate of interest based on the 30-day LIBOR plus a rate of 190 basis points. The interest rate for this mortgage loan has been fixed through the use of an interest rate swap that fixed the rate at 3.17%. The mortgage loan can be prepaid at any time subject to the termination of the interest rate swap.
Term of mortgage loan	5 years
Interest rate spread	1.90%