SECURED AND UNSECURED DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Decimal		Dec. 31, 2012
Secured and Unsecured Debt [Line Items]
Carrying Amount of Securing Real Estate	$ 470,368,000
Secured debt	499,793,000		607,766,000
Recourse liability	5,000,000
Payments of principal over the next five years [Abstract]
2014	48,862,000
2015	102,287,000
2016	92,717,000
2017	58,145,000
2018	141,218,000
Loans Payable, Noncurrent [Abstract]
Unsecured debt	305,000,000		130,000,000
$80 million Unsecured Term Loan [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate (in basis points)	175
Loans Payable, Noncurrent [Abstract]
Effective interest rate (in hundredths)	2.77%	[1]
Debt Instrument, Maturity Date	Aug. 15, 2018	[1]
Unsecured debt	80,000,000	[1]	80,000,000	[1]
$50 Million Unsecured Term Loan [Member]
Loans Payable, Noncurrent [Abstract]
Effective interest rate (in hundredths)	3.91%
Debt Instrument, Maturity Date	Dec. 21, 2018
Unsecured debt	50,000,000		50,000,000
$75 Million Unsecured Term Loan [Member]
Secured and Unsecured Debt [Line Items]
Debt instrument, spread above LIBOR variable rate (in basis points)	140
Loans Payable, Noncurrent [Abstract]
Effective interest rate (in hundredths)	3.752%	[2]
Debt Instrument, Maturity Date	Dec. 20, 2020	[2]
Unsecured debt	75,000,000	[2]	0	[2]
$100 million senior unsecured notes [Member]
Secured and Unsecured Debt [Line Items]
Principal Payment Due August 28, 2020	30,000,000
Principal Payment Due August 28, 2023	50,000,000
Principal Payment Due August 28, 2025	20,000,000
Loans Payable, Noncurrent [Abstract]
Effective interest rate (in hundredths)	3.80%	[3]
Debt Instrument, Maturity Date	Aug. 28, 2025	[3]
Unsecured debt	100,000,000	[3]	0	[3]
Thirty Fifth Avenue, Beltway I, Broadway V, Lockwood, Northwest Point, Sunbelt, Techway Southwest I and World Houston 10, 11 and 14 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	4.75%
Monthly P & I Payment	259,403
Maturity Date	Repaid
Carrying Amount of Securing Real Estate	0
Secured debt	0		34,474,000
Airport Commerce Center I and II, Interchange Park, Ridge Creek Distribution Center I, Southridge XII, Waterford Distribution Center and World Houston 24, 25 and 27 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.75%
Monthly P & I Payment	414,229
Maturity Date	Repaid
Carrying Amount of Securing Real Estate	0
Secured debt	0		52,086,000
Kyrene Distribution Center I [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	9.00%
Monthly P & I Payment	11,246
Maturity Date	7/1/2014
Carrying Amount of Securing Real Estate	4,059,000
Secured debt	76,000		198,000
Americas Ten I, Kirby, Palm River North I, II and III, Shady Trail, Westlake I and II and World Houston 17 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.68%
Monthly P & I Payment	175,479
Maturity Date	10/10/2014
Carrying Amount of Securing Real Estate	23,509,000
Secured debt	26,907,000		27,467,000
Beltway II, III and IV, Commerce Park 1, Eastlake, Fairgrounds I-IV, Nations Ford I-IV, Techway Southwest III, Wetmore I-IV and World Houston 15 and 22 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.50%
Monthly P & I Payment	536,552
Maturity Date	4/5/2015
Carrying Amount of Securing Real Estate	64,467,000
Secured debt	61,402,000		64,374,000
Country Club I, Lake Pointe, Techway Southwest II and World Houston 19 and 20 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	4.98%
Monthly P & I Payment	256,952
Maturity Date	12/5/2015
Carrying Amount of Securing Real Estate	20,534,000
Secured debt	27,812,000		29,465,000
Huntwood and Wiegman Distribution Centers [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.68%
Monthly P & I Payment	265,275
Maturity Date	9/5/2016
Carrying Amount of Securing Real Estate	20,631,000
Secured debt	28,833,000		30,332,000
Alamo Downs, Arion 1-15 and 17, Rampart I, II, III & IV, Santan 10 and World Houston 16 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.97%
Monthly P & I Payment	557,467
Maturity Date	11/5/2016
Carrying Amount of Securing Real Estate	54,487,000
Secured debt	60,131,000		63,132,000
Arion 16, Broadway VI, Chino, East University I and II, Northpark I-IV, Santan 10 II, 55th Avenue and World Houston 1 and 2, 21 and 23 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.57%
Monthly P & I Payment	518,885
Maturity Date	9/5/2017
Carrying Amount of Securing Real Estate	53,298,000
Secured debt	57,368,000		60,310,000
Dominguez, Industry I and III, Kingsview, Shaw, Walnut and Washington [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	7.50%	[4]
Monthly P & I Payment	539,747	[4]
Maturity Date	5/5/2019	[4]
Carrying Amount of Securing Real Estate	47,169,000	[4]
Secured debt	59,087,000	[4]	61,052,000	[4]
Blue Heron Distribution Center II [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	5.39%
Monthly P & I Payment	16,176
Maturity Date	2/29/2020
Carrying Amount of Securing Real Estate	4,430,000
Secured debt	1,026,000		1,161,000
Fortieth Avenue, Beltway V, Centennial Park, Executive Airport, Ocean View, Techway Southwest IV, Wetmore V-VIII and World Houston 26, 28, 29 and 30 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	4.39%
Monthly P & I Payment	463,778
Maturity Date	1/5/2021
Carrying Amount of Securing Real Estate	72,223,000
Secured debt	66,805,000		69,376,000
America Plaza, Central Green, Glenmont I & II, Interstate I, II & III, Rojas, Stemmons Circle, Venture, West Loop I & II and World Houston 3-9 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	4.75%
Monthly P & I Payment	420,045
Maturity Date	6/5/2021
Carrying Amount of Securing Real Estate	44,770,000
Secured debt	59,827,000		61,970,000
Arion 18, Beltway VI & VII, Commerce Park II & III, Concord Distribution Center, Interstate Distribution Center V, VI & VII, Lakeview Business Center, Ridge Creek Distribution Center II, Southridge IV & V and World Houston 32 [Member]
Secured and Unsecured Debt [Line Items]
Interest Rate (in hundredths)	4.09%
Monthly P & I Payment	329,796
Maturity Date	1/5/2022
Carrying Amount of Securing Real Estate	60,791,000
Secured debt	$ 50,519,000		$ 52,369,000

[1] The interest rate on this unsecured term loan is comprised of LIBOR plus 175 basis points subject to a pricing grid for changes in the Company's coverage ratings. The Company entered into an interest rate swap to convert the loan's LIBOR rate to a fixed interest rate, providing the Company an effective interest rate on the term loan of 2.770% as of December 31, 2013. See Note 13 for additional information on the interest rate swap.

[2] The interest rate on this unsecured term loan is comprised of LIBOR plus 140 basis points subject to a pricing grid for changes in the Company's coverage ratings. The Company entered into two interest rate swaps to convert the loan's LIBOR rate to a fixed interest rate, providing the Company a weighted average effective interest rate on the term loan of 3.752% as of December 31, 2013. See Note 13 for additional information on the interest rate swaps.

[3] Principal payments due on the $100 million senior unsecured notes are as follows: $30 million on August 28, 2020, $50 million on August 28, 2023, and $20 million on August 28, 2025.

[4] This mortgage loan has a recourse liability of $5.0 million which will be released based on the secured properties generating certain base rent amounts.