NOTES AND BOND PAYABLE (Schedule of Long-term Debt Instruments) (Details) (USD $)				0 Months Ended	9 Months Ended				0 Months Ended	9 Months Ended				0 Months Ended	9 Months Ended				0 Months Ended		9 Months Ended				0 Months Ended				9 Months Ended				0 Months Ended			9 Months Ended				0 Months Ended			9 Months Ended				0 Months Ended	9 Months Ended				0 Months Ended			9 Months Ended
	Sep. 30, 2013		Dec. 31, 2012	Nov. 23, 2011 Mortgages [Member] Richardson Joint Venture [Member]	Sep. 30, 2013 Mortgages [Member] Richardson Joint Venture [Member]		Nov. 23, 2011 Mortgages [Member] Richardson Joint Venture [Member] Maximum [Member]	Sep. 30, 2013 Mortgages [Member] Richardson Joint Venture [Member] Minimum [Member]	Jan. 11, 2013 Richardson Portfolio [Member]	Sep. 30, 2013 Richardson Portfolio [Member] Mortgages [Member]		Dec. 31, 2012 Richardson Portfolio [Member] Mortgages [Member]		Feb. 22, 2013 Bellevue Technology Center [Member] Mortgages [Member]	Sep. 30, 2013 Bellevue Technology Center [Member] Mortgages [Member]		Dec. 31, 2012 Bellevue Technology Center [Member] Mortgages [Member]		Feb. 22, 2013 Bellevue Technology Center [Member] Mortgages [Member] Beginning March 1, 2016 [Member]	Feb. 22, 2013 Bellevue Technology Center [Member] Mortgages [Member] Maximum [Member]	Sep. 30, 2013 Portfolio Revolving Loan Facility [Member] Mortgages [Member]		Dec. 31, 2012 Portfolio Revolving Loan Facility [Member] Mortgages [Member]		May 01, 2013 Portfolio Revolving Loan Facility [Member] Secured Debt [Member] Mortgages [Member]	May 01, 2013 Portfolio Revolving Loan Facility [Member] Secured Debt [Member] Mortgages [Member] Beginning June 1, 2016 [Member]	May 01, 2013 Portfolio Revolving Loan Facility [Member] Revolving Credit Facility [Member]	May 01, 2013 Portfolio Revolving Loan Facility [Member] Non-Revolving Credit Facility [Member]	Sep. 30, 2013 Portfolio Mortgage Loan [Member] Mortgages [Member]		Dec. 31, 2012 Portfolio Mortgage Loan [Member] Mortgages [Member]		Jun. 26, 2013 Portfolio Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 30, 2013 Portfolio Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Jun. 26, 2013 Portfolio Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member] Debt Service Coverage Ratio of at Least 1.25 [Member]	Sep. 30, 2013 1635 N. Cahuenga Mortgage Loan [Member] Mortgages [Member]		Dec. 31, 2012 1635 N. Cahuenga Mortgage Loan [Member] Mortgages [Member]		Sep. 30, 2013 1635 N. Cahuenga Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Jul. 24, 2013 1635 N. Cahuenga Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Aug. 02, 2013 1635 N. Cahuenga Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 30, 2013 Burbank Collection Mortgage Loan [Member] Mortgages [Member]		Dec. 31, 2012 Burbank Collection Mortgage Loan [Member] Mortgages [Member]		Sep. 10, 2013 Burbank Collection Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 30, 2013 50 Congress Mortgage Loan [Member] Mortgages [Member]		Dec. 31, 2012 50 Congress Mortgage Loan [Member] Mortgages [Member]		Sep. 30, 2013 50 Congress Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 25, 2013 50 Congress Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 26, 2013 50 Congress Mortgage Loan [Member] Secured Debt [Member] Mortgages [Member]	Sep. 30, 2013 1180 Raymond Bond [Member] Mortgages [Member]		Dec. 31, 2012 1180 Raymond Bond [Member] Mortgages [Member]
Debt Instrument [Line Items]
Notes payable							$ 46,100,000			$ 30,457,000	[1]	$ 33,751,000	[1]		$ 44,450,000	[2]	$ 0	[2]		$ 53,000,000	$ 0	[3]	$ 0	[3]					$ 80,668,000	[4]	$ 0	[4]				$ 4,650,000	[5]	$ 0	[5]				$ 8,200,000		$ 0	[6]		$ 26,535,000		$ 0	[7]
Bonds payable																																																							7,120,000		0
Total Notes and Bond Payable principal outstanding	202,080,000		33,751,000
Premium on Bond Payable, net	1,600,000	[8]
Total notes and bond payable, net	203,680,000		33,751,000
Basis spread on variable rate					4.00%	[1],[9]									2.25%	[2],[9]					2.25%	[3],[9]			2.25%				2.50%	[4],[9]			2.50%		2.25%	2.35%	[5],[9]					2.35%					2.35%							1.90%
Description of variable rate basis					three-month LIBOR	[1],[9]									one-month LIBOR	[2],[9]					one-month LIBOR	[3],[9]							one-month LIBOR	[4],[9]						one-month LIBOR	[5],[9]			one-month LIBOR							one-month LIBOR					one-month LIBOR
Contractual interest rate, percentage								6.25%																																															6.50%
Interest rate, effective percentage										6.25%	[1],[9]				2.43%	[2],[9]													2.68%	[4],[9]						2.53%							2.53%					2.08%							6.50%
Payment terms										Interest Only	[1]				Interest Only	[2]					Interest Only	[3]							Interest Only	[4]						Interest Only	[5]						Interest Only	[6]				Interest Only	[7]						Principal & Interest	[7]
Maturity date										Nov. 30, 2015	[1],[10]				Mar. 01, 2017	[10],[2]					May 01, 2017	[10],[3]							Jul. 01, 2017	[10],[4]						Aug. 01, 2016	[10],[5]						Sep. 30, 2016	[10],[6]				Oct. 01, 2017	[10],[7]						Sep. 01, 2036	[10],[7]
Term of credit facility				4 years										4 years											four								4 years								3 years						3 years						4 years
Amount outstanding				29,500,000	30,500,000									44,500,000																				80,700,000								4,700,000					8,200,000					26,500,000
Unused borrowing capacity, amount				16,600,000	9,400,000									8,500,000																				39,300,000						2,000,000							3,000,000
Repayments of debt									5,200,000
Periodic payment																			60,000							80,000
Amortization schedule of mortgage loans on real estate																																	30 years
Current capacity																									72,500,000								120,000,000								6,700,000						11,200,000					6,300,000
Maximum borrowing capacity																											$ 59,500,000	$ 13,000,000																									$ 32,900,000
Interest rate during period																																	6.00%

[1] On November 23, 2011, the Richardson Joint Venture entered into a four-year mortgage loan for borrowings up to $46.1 million. At closing, $29.5 million (the “Initial Funding”) had been disbursed to the Richardson Joint Venture and $16.6 million (the “Holdback”) remained available for future disbursements, subject to certain conditions set forth in the loan agreement. On January 11, 2013, the Company sold one of the properties in the Richardson Portfolio and repaid $5.2 million of the Initial Funding. As of September 30, 2013, the outstanding principal balance was $30.5 million and $9.4 million of the Holdback remains available for future disbursements, subject to certain conditions set forth in the loan agreement. Interest on the Initial Funding is calculated at a fixed rate of 6.25% during the initial term of the loan. Interest on the Holdback is calculated at a variable annual rate of 400 basis points over three-month LIBOR, but at no point shall the interest rate be less than 6.25%.

[2] On February 22, 2013, the Company entered into a four-year mortgage loan for borrowings up to $53.0 million. As of September 30, 2013, $44.5 million had been disbursed to the Company and the remaining $8.5 million is available for future disbursements to be used for tenant improvements, leasing commissions and capital improvements, subject to certain conditions contained in the loan documents. Monthly payments are initially interest only. Beginning March 1, 2016, monthly payments also include principal amortization payments of up to $60,000 per month.

[3] On May 1, 2013, the Company, through its indirect wholly owned subsidiaries, entered into a four-year secured mortgage loan for borrowings of up to $72.5 million secured by the 1800 West Loop Building and the Iron Point Business Park (the “Portfolio Revolving Loan Facility”). The Portfolio Revolving Loan Facility is comprised of $59.5 million of revolving debt and $13.0 million of non-revolving debt available to be used for tenant improvements, leasing commissions and capital improvements, subject to certain terms and conditions contained in the loan documents. As of September 30, 2013, the Company had no outstanding principal amount. Monthly payments are initially interest only. Beginning June 1, 2016, and to the extent that there are amounts outstanding under the non-revolving portion of the loan, monthly payments will include interest and principal amortization payments of up to $80,000 per month.

[4] On June 26, 2013, the Company, through its indirect wholly owned subsidiaries, entered into a four-year secured mortgage loan for borrowings of up to $120.0 million secured by Northridge Center I & II, Powers Ferry Landing East, West Loop I & II and the Austin Suburban Portfolio (the “Portfolio Mortgage Loan”). As of September 30, 2013, $80.7 million had been disbursed to the Company with the remaining $39.3 million available for future disbursements to be used for tenant improvements, leasing commissions and capital improvements, subject to certain terms and conditions contained in the loan documents. Monthly payments are initially interest only. Beginning July 1, 2016, monthly payments will include principal and interest with principal payments calculated using an amortization schedule of 30 years and an assumed annual interest rate of 6.0%.

[5] See “- Recent Transactions - 1635 N. Cahuenga Mortgage Loan” below.

[6] See “- Recent Transactions - Burbank Collection Mortgage Loan” below.

[7] See “- Recent Transactions - 50 Congress Mortgage Loan” below.

[8] Represents the unamortized premium on bond payable due to the above-market interest rates when the bond was assumed. The premium is amortized over the remaining life of the bond.

[9] Contractual interest rate represents the interest rate in effect under the loan as of September 30, 2013. Effective interest rate is calculated as the actual interest rate in effect as of September 30, 2013 (consisting of the contractual interest rate and contractual floor rates), using interest rate indices at September 30, 2013, where applicable.

[10] Represents the initial maturity date or the maturity date as extended as of September 30, 2013; subject to certain conditions, the maturity dates of certain loans may be extended beyond the date shown.