UNSECURED AND SECURED DEBT (Tables)

12 Months Ended

Dec. 31, 2018

Debt Instrument [Line Items]

Schedule of long-term debt instruments

	December 31, 2018			December 31, 2017
	(In thousands)
Unsecured bank credit facilities - variable rate, carrying amount	$	195,730		116,339
Unsecured bank credit facilities - fixed rate, carrying amount(1) (2)	—			80,000
Unamortized debt issuance costs	(1,804		)	(630	)
Unsecured bank credit facilities	193,926			195,709
Unsecured debt - fixed rate, carrying amount (1)	725,000			715,000
Unamortized debt issuance costs	(1,600		)	(1,939	)
Unsecured debt	723,400			713,061
Secured debt - fixed rate, carrying amount (1)	189,038			200,354
Unamortized debt issuance costs	(577		)	(842	)
Secured debt	188,461			199,512
Total debt	$	1,105,787		1,108,282

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

(2) The Company had designated an interest rate swap to an $80 million unsecured bank credit facility draw that effectively fixed the interest rate on the $80 million draw to 2.020% through the interest rate swap's maturity date. This swap matured on August 15, 2018, and the $80 million draw has reverted to the variable interest rate associated with the Company's unsecured bank credit facilities. 

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	2018		2017
				(In thousands)
$50 Million Unsecured Term Loan	Not applicable	3.910%	12/21/2018	$	—	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)	1.100%	3.452%	12/20/2020	75,000		75,000
$40 Million Unsecured Term Loan (1)	1.100%	2.335%	07/30/2021	40,000		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)	1.100%	2.313%	04/01/2023	65,000		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
$60 Million Senior Unsecured Notes	Not applicable	3.460%	12/13/2024	60,000		60,000
$100 Million Senior Unsecured Notes:
$60 Million Notes	Not applicable	3.480%	12/15/2024	60,000		60,000
$40 Million Notes	Not applicable	3.750%	12/15/2026	40,000		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
$60 Million Senior Unsecured Notes	Not applicable	3.930%	04/10/2028	60,000		—
				$	725,000	715,000

(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, 2018.

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, 2018		Balance at December 31,
Property						2018	2017
				(In thousands)
Dominguez, Industry I & III, Kingsview, Shaw, Walnut and Washington	7.50%	539,747	05/05/2019	$	45,420	46,725	49,580
Blue Heron II	5.39%	16,176	02/29/2020	4,555		233	409
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	66,493		52,115	55,317
Colorado Crossing, Interstate I-III, Rojas, Steele Creek 1 & 2, Venture and World Houston 3-9 (1)	4.75%	420,045	06/05/2021	53,820		47,445	50,161
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	54,679		40,046	42,315
Ramona	3.85%	16,287	11/30/2026	8,890		2,474	2,572
				$	233,857	189,038	200,354

(1) Subsequent to December 31, 2018, the Company executed a collateral release for World Houston 5; this property is no longer considered to be collateral securing this loan.

Principal payments due during the next five years

Scheduled 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, 2018 are as follows: 

Years Ending December 31,	(In thousands)
2019	$	130,567
2020	114,096
2021	129,563
2022	107,769
2023	115,119