SCHEDULE III (Details2) - USD ($)		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at beginning of year	[1]	$ 3,519,085,000		$ 3,264,566,000	$ 2,817,145,000
Purchases of real estate properties		104,205,000		46,240,000	135,033,000
Development of real estate properties		415,260,000		195,446,000	318,288,000
Improvements to real estate properties		36,692,000		33,522,000	37,558,000
Right-of-use asset, net - ground leases		11,562,000		(924,000)	11,997,000
SEC Schedule 12-29, Real Estate Companies, Investment in real estate, real estate held for sale		(18,233,000)		0	0
Carrying amount of investments sold		(15,288,000)		(17,182,000)	(51,662,000)
Write-off of improvements		(1,958,000)		(2,583,000)	(3,793,000)
Balance at end of year	[1]	4,051,325,000	[2],[3]	3,519,085,000	3,264,566,000
Noncontrolling Interests		1,379,000		852,000	3,148,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at beginning of year		955,328,000		871,139,000	814,915,000
Depreciation expense		104,910,000		96,290,000	86,590,000
Real estate assets held for sale		(12,538,000)		0	0
Accumulated depreciation on assets sold		(10,178,000)		(9,599,000)	(27,030,000)
Other		(1,905,000)		(2,502,000)	(3,336,000)
Balance at end of year		1,035,617,000	[2],[3]	$ 955,328,000	$ 871,139,000
Estimated aggregate cost of real estate properties for federal income tax purposes		3,974,390,000
Estimated accumulated tax depreciation		$ 749,711,000
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
Industrial Development [Member]
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at end of year		$ 504,614,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at end of year		$ 519,000
Development properties [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Percentage of Occupation when property transfers from the development and value-add program to real estate properties		90.00%
Value-add properties [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Percentage of Occupation when property transfers from the development and value-add program to real estate properties		90.00%
Development and value-add properties [Member]
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Percentage of Occupation When Costs Ceased Being Capitalized for development and value-add properties		90.00%

[1] Includes noncontrolling interest in joint ventures of $1,379,000, $852,000 and $3,148,000 at December 31, 2021, 2020 and 2019, respectively.

[2] Changes in Real Estate Properties and Development and Value-Add Properties follow:                                                                                                                                                                                                                                                                                                                                                                                    Years Ended December 31,202120202019(In thousands)Balance at beginning of year $3,519,085 3,264,566 2,817,145 Purchases of real estate properties 104,205 46,240 135,033 Development of real estate properties and value-add properties415,260 195,446 318,288 Improvements to real estate properties36,692 33,522 37,558 Right-of-use assets, net – ground leases11,562 (924)11,997 Real estate assets held for sale(18,233)— — Carrying amount of investments sold (15,288)(17,182)(51,662)Write-off of improvements (1,958)(2,583)(3,793) Balance at end of year (1)  $4,051,325 3,519,085 3,264,566 
(1) Includes noncontrolling interest in joint ventures of $1,379,000, $852,000 and $3,148,000 at December 31, 2021, 2020 and 2019, respectively.
Changes in the accumulated depreciation on real estate properties follow:                                                                                                                                                                                                                                                                                                                                                                                   Years Ended December 31,202120202019(In thousands)Balance at beginning of year $955,328 871,139 814,915 Depreciation expense 104,910 96,290 86,590 Real estate assets held for sale(12,538)— — Accumulated depreciation on assets sold (10,178)(9,599)(27,030)Other (1,905)(2,502)(3,336)Balance at end of year $1,035,617 955,328 871,139 

[3] The estimated aggregate cost of real estate properties at December 31, 2021 for federal income tax purposes was approximately $3,974,390,000 before estimated accumulated tax depreciation of $749,711,000.  The federal income tax return for the year ended December 31, 2021, has not been filed and accordingly, this estimate is based on preliminary data.