Real Estate and Accumulated Depreciation (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 203,194
Buildings & Improvements, Initial Cost		978,644
Land, Total Cost		205,622
Buildings & Improvements, Total Cost		1,220,779
Total Cost		1,426,401
Accumulated Depreciation		654,389
Total Cost, Net of Accumulated Depreciation		772,012
Encumbrances		306,762
The changes in Total Real Estate Assets for the three years ended December 31, are as follows:
Balance at beginning of year		3,820,352	$ 4,598,591	$ 4,713,523
Acquisitions		17,790	0	37,886
Developments, improvements and expansions		39,397	84,972	91,921
Adjustments of property carrying values (impairments)		(66,600)	0	(2,536)
Disposals(A)		(2,384,538)	(863,211)	(242,203)
Balance at end of year		1,426,401	3,820,352	4,598,591
The changes in Accumulated Depreciation and Amortization for the three years ended December 31, are as follows:
Balance at beginning of year		1,434,209	1,539,338	1,473,102
Depreciation for year		93,674	166,061	157,120
Disposals		(873,494)	(271,190)	(90,884)
Balance at end of year		654,389	$ 1,434,209	$ 1,539,338
Phoenix, AZ [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		13,069
Buildings & Improvements, Initial Cost		14,751
Land, Total Cost		13,069
Buildings & Improvements, Total Cost		21,675
Total Cost		34,744
Accumulated Depreciation		12,022
Total Cost, Net of Accumulated Depreciation		22,722
Encumbrances		$ 16,015
Date of Construction (C) Acquisition (A)		1999
Phoenix, AZ [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 7,856
Buildings & Improvements, Initial Cost		14,926
Land, Total Cost		7,613
Buildings & Improvements, Total Cost		17,007
Total Cost		24,620
Accumulated Depreciation		11,934
Total Cost, Net of Accumulated Depreciation		12,686
Encumbrances		$ 17,421
Date of Construction (C) Acquisition (A)		2003
Long Beach, CA [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 0
Buildings & Improvements, Initial Cost		147,918
Land, Total Cost		0
Buildings & Improvements, Total Cost		205,227
Total Cost		205,227
Accumulated Depreciation		129,937
Total Cost, Net of Accumulated Depreciation		75,290
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2005
Colorado Springs, CO [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 4,111
Buildings & Improvements, Initial Cost		22,140
Land, Total Cost		4,111
Buildings & Improvements, Total Cost		28,333
Total Cost		32,444
Accumulated Depreciation		10,154
Total Cost, Net of Accumulated Depreciation		22,290
Encumbrances		$ 9,990
Date of Construction (C) Acquisition (A)		2011
Parker, CO [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 680
Buildings & Improvements, Initial Cost		8,398
Land, Total Cost		680
Buildings & Improvements, Total Cost		8,824
Total Cost		9,504
Accumulated Depreciation		3,198
Total Cost, Net of Accumulated Depreciation		6,306
Encumbrances		$ 4,377
Date of Construction (C) Acquisition (A)		2003
Parker, CO [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 398
Buildings & Improvements, Initial Cost		21,512
Land, Total Cost		398
Buildings & Improvements, Total Cost		26,126
Total Cost		26,524
Accumulated Depreciation		9,354
Total Cost, Net of Accumulated Depreciation		17,170
Encumbrances		$ 9,163
Date of Construction (C) Acquisition (A)		2003
Fort Walton Beach, FL [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 3,643
Buildings & Improvements, Initial Cost		5,612
Land, Total Cost		3,462
Buildings & Improvements, Total Cost		5,578
Total Cost		9,040
Accumulated Depreciation		1,101
Total Cost, Net of Accumulated Depreciation		7,939
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2021
Winter Garden, FL [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 18,605
Buildings & Improvements, Initial Cost		105,037
Land, Total Cost		19,124
Buildings & Improvements, Total Cost		114,249
Total Cost		133,373
Accumulated Depreciation		45,985
Total Cost, Net of Accumulated Depreciation		87,388
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2013
Atlanta, GA [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 14,078
Buildings & Improvements, Initial Cost		41,050
Land, Total Cost		14,078
Buildings & Improvements, Total Cost		48,841
Total Cost		62,919
Accumulated Depreciation		24,293
Total Cost, Net of Accumulated Depreciation		38,626
Encumbrances		$ 23,447
Date of Construction (C) Acquisition (A)		2009
Roswell, GA [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 6,566
Buildings & Improvements, Initial Cost		15,005
Land, Total Cost		7,894
Buildings & Improvements, Total Cost		29,925
Total Cost		37,819
Accumulated Depreciation		16,628
Total Cost, Net of Accumulated Depreciation		21,191
Encumbrances		$ 10,486
Date of Construction (C) Acquisition (A)		2007
Chicago, IL [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 22,642
Buildings & Improvements, Initial Cost		82,754
Land, Total Cost		22,642
Buildings & Improvements, Total Cost		85,122
Total Cost		107,764
Accumulated Depreciation		30,363
Total Cost, Net of Accumulated Depreciation		77,401
Encumbrances		$ 29,145
Date of Construction (C) Acquisition (A)		2014
Chicago, IL [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 23,588
Buildings & Improvements, Initial Cost		45,632
Land, Total Cost		23,588
Buildings & Improvements, Total Cost		46,066
Total Cost		69,654
Accumulated Depreciation		13,830
Total Cost, Net of Accumulated Depreciation		55,824
Encumbrances		$ 30,383
Date of Construction (C) Acquisition (A)		2017
Brentwood, MO [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 10,018
Buildings & Improvements, Initial Cost		32,053
Land, Total Cost		10,018
Buildings & Improvements, Total Cost		41,336
Total Cost		51,354
Accumulated Depreciation		31,258
Total Cost, Net of Accumulated Depreciation		20,096
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		1998
East Hanover, NJ [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 3,847
Buildings & Improvements, Initial Cost		23,798
Land, Total Cost		3,847
Buildings & Improvements, Total Cost		30,081
Total Cost		33,928
Accumulated Depreciation		17,842
Total Cost, Net of Accumulated Depreciation		16,086
Encumbrances		$ 9,908
Date of Construction (C) Acquisition (A)		2007
Edgewater, NJ [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 7,714
Buildings & Improvements, Initial Cost		30,473
Land, Total Cost		7,714
Buildings & Improvements, Total Cost		49,814
Total Cost		57,528
Accumulated Depreciation		21,915
Total Cost, Net of Accumulated Depreciation		35,613
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2007
Princeton, NJ [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 17,991
Buildings & Improvements, Initial Cost		82,063
Land, Total Cost		18,998
Buildings & Improvements, Total Cost		131,619
Total Cost		150,617
Accumulated Depreciation		85,409
Total Cost, Net of Accumulated Depreciation		65,208
Encumbrances		$ 99,862
Date of Construction (C) Acquisition (A)		1997
Chapel Hill, NC [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 5,641
Buildings & Improvements, Initial Cost		3,727
Land, Total Cost		5,641
Buildings & Improvements, Total Cost		3,727
Total Cost		9,368
Accumulated Depreciation		111
Total Cost, Net of Accumulated Depreciation		9,257
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2024
Chapel Hill, NC [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 4,500
Buildings & Improvements, Initial Cost		2,892
Land, Total Cost		4,500
Buildings & Improvements, Total Cost		2,969
Total Cost		7,469
Accumulated Depreciation		98
Total Cost, Net of Accumulated Depreciation		7,371
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		2024
Stow, OH [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 993
Buildings & Improvements, Initial Cost		9,028
Land, Total Cost		993
Buildings & Improvements, Total Cost		48,669
Total Cost		49,662
Accumulated Depreciation		31,779
Total Cost, Net of Accumulated Depreciation		17,883
Encumbrances		$ 0
Date of Construction (C) Acquisition (A)		1969
Portland, OR [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 10,122
Buildings & Improvements, Initial Cost		37,457
Land, Total Cost		10,122
Buildings & Improvements, Total Cost		38,639
Total Cost		48,761
Accumulated Depreciation		6,989
Total Cost, Net of Accumulated Depreciation		41,772
Encumbrances		$ 14,614
Date of Construction (C) Acquisition (A)		2019
Easton, PA [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 7,691
Buildings & Improvements, Initial Cost		20,405
Land, Total Cost		7,691
Buildings & Improvements, Total Cost		21,792
Total Cost		29,483
Accumulated Depreciation		4,372
Total Cost, Net of Accumulated Depreciation		25,111
Encumbrances		$ 17,502
Date of Construction (C) Acquisition (A)		2020
Richmond, VA [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost		$ 11,879
Buildings & Improvements, Initial Cost		34,736
Land, Total Cost		11,879
Buildings & Improvements, Total Cost		37,883
Total Cost		49,762
Accumulated Depreciation		21,588
Total Cost, Net of Accumulated Depreciation		28,174
Encumbrances		$ 14,449
Date of Construction (C) Acquisition (A)		2007
Portfolio Balance [Member]
Real Estate And Accumulated Depreciation [Line Items]
Land, Initial Cost	[1]	$ 7,562
Buildings & Improvements, Initial Cost	[1]	177,277
Land, Total Cost	[1]	7,560
Buildings & Improvements, Total Cost	[1]	177,277
Total Cost	[1]	184,837
Accumulated Depreciation	[1]	124,229
Total Cost, Net of Accumulated Depreciation	[1]	60,608
Encumbrances	[1]	$ 0

[1] Includes the Company’s Beachwood headquarters and related fixtures and equipment as well as $0.9 million of undeveloped land and $1.8 million of construction in progress at December 31, 2024.