UNSECURED AND SECURED DEBT (Tables)

12 Months Ended

Dec. 31, 2016

Debt Instrument [Line Items]

Schedule of long-term debt instruments

	December 31, 2016			December 31, 2015
	(In thousands)
Unsecured bank credit facilities - variable rate, carrying amount	$	112,020		150,836
Unsecured bank credit facilities - fixed rate, carrying amount(1)	80,000			—
Unamortized debt issuance costs	(1,030		)	(1,422	)
Unsecured bank credit facilities	190,990			149,414
Unsecured debt - fixed rate, carrying amount (1)	655,000			530,000
Unamortized debt issuance costs	(2,162		)	(1,790	)
Unsecured debt	652,838			528,210
Secured debt - fixed rate, carrying amount (1)	258,594			351,401
Unamortized debt issuance costs	(1,089		)	(1,116	)
Secured debt	257,505			350,285
Total debt	$	1,101,333		1,027,909

(1) These loans have a fixed interest rate or an effectively fixed interest rate due to interest rate swaps.

Schedule of unsecured debt [Table Text Block]

A summary of the carrying amount of Unsecured debt follows:

				Balance at December 31,
	Margin Above LIBOR	Interest Rate	Maturity Date	2016		2015
				(In thousands)
$80 Million Unsecured Term Loan (1)	1.750%	2.770%	08/15/2018	$	—	80,000
$50 Million Unsecured Term Loan	Not applicable	3.910%	12/21/2018	50,000		50,000
$75 Million Unsecured Term Loan (1)	1.150%	2.846%	07/31/2019	75,000		75,000
$75 Million Unsecured Term Loan (1)	1.400%	3.752%	12/20/2020	75,000		75,000
$40 Million Unsecured Term Loan (1)	1.100%	2.335%	07/30/2021	40,000		—
$75 Million Unsecured Term Loan (1)	1.400%	3.031%	02/28/2022	75,000		75,000
$65 Million Unsecured Term Loan (1)	1.650%	2.863%	04/01/2023	65,000		—
$100 Million Senior Unsecured Notes:
$30 Million Notes	Not applicable	3.800%	08/28/2020	30,000		30,000
$50 Million Notes	Not applicable	3.800%	08/28/2023	50,000		50,000
$20 Million Notes	Not applicable	3.800%	08/28/2025	20,000		20,000
$100 Million Senior Unsecured Notes:
$60 Million Notes	Not applicable	3.480%	12/15/2024	60,000		—
$40 Million Notes	Not applicable	3.750%	12/15/2026	40,000		—
$25 Million Senior Unsecured Notes	Not applicable	3.970%	10/01/2025	25,000		25,000
$50 Million Senior Unsecured Notes	Not applicable	3.990%	10/07/2025	50,000		50,000
				$	655,000	530,000

(1) The interest rates on these unsecured term loans are comprised of LIBOR plus a margin which is subject to a pricing grid for changes in the Company's coverage ratings. The Company entered into interest rate swap agreements (further described in Note 13) to convert the loans' LIBOR rates to effectively fixed interest rates. The interest rates in the table above are the effectively fixed interest rates for the loans, including the effects of the interest rate swaps, as of December 31, 2016.

Secured debt

A summary of the carrying amount of Secured debt follows: 

	Interest Rate	Monthly P&I Payment	Maturity Date	Carrying Amount of Securing Real Estate at December 31, 2016		Balance at December 31,
Property						2016	2015
				(In thousands)
Huntwood and Wiegman I	5.68%	265,275	Repaid	$	—	—	25,567
Alamo Downs, Arion 1-15 & 17, Rampart I-IV, Santan 10 I and World Houston 16	5.97%	557,467	Repaid	—		—	53,563
Arion 16, Broadway VI, Chino, East University I & II, Northpark, Santan 10 II, 55th Avenue and World Houston 1 & 2, 21 & 23	5.57%	518,885	09/05/2017	47,514		47,496	50,971
Dominguez, Industry I & III, Kingsview, Shaw, Walnut and Washington (1)	7.50%	539,747	05/05/2019	46,755		52,231	54,689
Blue Heron II	5.39%	16,176	02/29/2020	4,208		576	735
40th Avenue, Beltway Crossing V, Centennial Park, Executive Airport, Interchange Park I, Ocean View, Wetmore 5-8 and World Houston 26, 28, 29 & 30	4.39%	463,778	01/05/2021	69,029		58,380	61,312
Colorado Crossing, Interstate I-III, Rojas, Steele Creek 1 & 2, Stemmons Circle, Venture and World Houston 3-9	4.75%	420,045	06/05/2021	59,882		52,752	55,223
Arion 18, Beltway Crossing VI & VII, Commerce Park II & III, Concord, Interstate V-VII, Lakeview, Ridge Creek II, Southridge IV & V and World Houston 32	4.09%	329,796	01/05/2022	58,425		44,493	46,584
Ramona	3.85%	16,287	11/30/2026	9,185		2,666	2,757
				$	294,998	258,594	351,401

(1) 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.

Principal payments due during the next five years

Principal payments on long-term debt, including Unsecured debt and Secured debt (not including Unsecured bank credit facilities), due during the next five years as of December 31, 2016 are as follows: 

Years Ending December 31,	(In thousands)
2017	$	58,237
2018	61,316
2019	130,569
2020	114,096
2021	129,563