SCHEDULE III SCHEDULE III (Details2) - USD ($)		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at beginning of year	[1]	$ 2,074,946,000		$ 1,927,326,000	$ 1,768,032,000
Purchases of real estate properties		28,648,000		47,477,000	65,387,000
Development of real estate properties		95,032,000		97,696,000	76,240,000
Improvements to real estate properties		25,778,000		19,862,000	21,438,000
Carrying amount of investments sold		(4,750,000)		(17,049,000)	(3,475,000)
Write-off of improvements		(206,000)		(366,000)	(296,000)
Balance at end of year	[1]	2,219,448,000	[2],[3]	2,074,946,000	1,927,326,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at beginning of year		600,526,000		550,113,000	496,247,000
Depreciation expense		59,882,000		57,303,000	54,284,000
Accumulated depreciation on assets sold		(2,748,000)		(6,525,000)	(126,000)
Other		(206,000)		(365,000)	(292,000)
Balance at end of year		657,454,000	[2],[3]	600,526,000	$ 550,113,000
Estimated aggregate cost of real estate properties for federal income tax purposes		2,188,766,000
Estimated accumulated tax depreciation		$ 425,700,000
Percentage of Occupation When Development Cost Ceased Being Capitalized		80.00%
Length of Time After Project Completion When Development Cost Ceased Being Capitalized		1 year
Secured debt		$ 351,401,000		453,776,000
Recourse liability		$ 5,000,000
Castilian Research Center [Member]
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Noncontrolling Interests (in hundreths)		20.00%
Noncontrolling Interests		$ 1,795,000		1,794,000
University Business Center [Member]
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Noncontrolling Interests (in hundreths)		20.00%
Noncontrolling Interests		$ 6,670,000		6,536,000
Buildings [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Estimated useful life (in years)		40 years
Minimum [Member] | Improvements and Personal Property [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Estimated useful life (in years)		3 years
Maximum [Member] | Improvements and Personal Property [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Estimated useful life (in years)		15 years
Dominguez, Industry I and III, Kingsview, Shaw, Walnut and Washington [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt	[4]	$ 54,689,000		56,970,000
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]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		50,971,000		54,259,000
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]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		55,223,000		57,579,000
Arion 18, Beltway VI & VII, Commerce Park II & III, Concord Dist Ctr, Interstate Dist Ctr V, VI & VII, Lakeview Business Ctr, Ridge Creek Distribution Ctr II, Southridge IV & V and World Houston 32 [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		46,584,000		48,592,000
Country Club I, Lake Pointe, Techway Southwest II and World Houston 19 and 20 [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		0		26,074,000
Huntwood and Wiegman I-IV Distribution Centers [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		25,567,000		27,246,000
Alamo Downs, Arion 1-15 and 17, Rampart I, II, III & IV, Santan 10 and World Houston 16 [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		53,563,000		56,945,000
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]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		0		58,262,000
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]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Secured debt		$ 61,312,000		$ 64,119,000

[1] Includes 20% noncontrolling interests in Castilian Research Center of $1,795,000 at December 31, 2015 and $1,794,000 at December 31, 2014 and in University Business Center of $6,670,000 and $6,536,000, respectively.

[2] Changes in Real Estate Properties follow: Years Ended December 31,2015 2014 2013(In thousands)Balance at beginning of year $2,074,946 1,927,326 1,768,032Purchases of real estate properties 28,648 47,477 65,387Development of real estate properties95,032 97,696 76,240Improvements to real estate properties25,778 19,862 21,438Carrying amount of investments sold (4,750) (17,049) (3,475)Write-off of improvements (206) (366) (296)Balance at end of year (1) $2,219,448 2,074,946 1,927,326(1)Includes 20% noncontrolling interests in Castilian Research Center of $1,795,000 at December 31, 2015 and $1,794,000 at December 31, 2014 and in University Business Center of $6,670,000 and $6,536,000, respectively.Changes in the accumulated depreciation on real estate properties follow: Years Ended December 31,2015 2014 2013(In thousands)Balance at beginning of year $600,526 550,113 496,247Depreciation expense 59,882 57,303 54,284Accumulated depreciation on assets sold (2,748) (6,525) (126)Other (206) (365) (292)Balance at end of year $657,454 600,526 550,113

[3] The estimated aggregate cost of real estate properties at December 31, 2015 for federal income tax purposes was approximately $2,188,766,000 before estimated accumulated tax depreciation of $425,700,000. The federal income tax return for the year ended December 31, 2015, has not been filed and accordingly, this estimate is based on preliminary data.

[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.