Schedule III - Consolidated Real Estate and Accumulated Depreciation (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2018
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Balance at beginning of year	$ 535,583	$ 508,170
Property acquisitions	33,061	25,563
Improvements	2,180	1,850
Balance at end of year	570,824	535,583
Balance at beginning of year	104,163	93,785
Depreciation and amortization for year	10,363	10,378
Balance at end of year	114,526	$ 104,163
Principal Outstanding	486,822
American International Group 2022 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	225,000
Allstate Corporation [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	33,945
United States Life Insurance Company [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	39,000
United States Life Insurance Company [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	32,059
Transamerica Life Insurance Company [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	7,809
Transamerica Life Insurance Company [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	25,000
American General Life Insurance Company [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Principal Outstanding	124,009
Connecticut [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Balance at end of year	103,938
Balance at end of year	$ 28,180
Connecticut [Member] | 35 Executive Blvd., Orange, CT [Member] | American International Group 2022 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Write-down of carrying value related to demolished asset			$ 7,500