REAL ESTATE - Schedule of Real Estate Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Real Estate Properties [Line Items]
Total real estate held for investment, cost	$ 2,244,923	$ 2,367,669
Accumulated depreciation and amortization	(681,392)	(659,799)
Total real estate, net	1,563,531	$ 1,839,478
Town Center | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	143,310
Accumulated depreciation and amortization	(58,514)
Total real estate, net	84,796
Gateway Tech Center | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	37,388
Accumulated depreciation and amortization	(14,095)
Total real estate, net	23,293
60 South Sixth | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	115,520
Accumulated depreciation and amortization	(1,825)
Total real estate, net	113,695
Sterling Plaza | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	97,086
Accumulated depreciation and amortization	(36,020)
Total real estate, net	61,066
Accenture Tower | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	575,455
Accumulated depreciation and amortization	(184,634)
Total real estate, net	390,821
Ten Almaden | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	131,599
Accumulated depreciation and amortization	(45,433)
Total real estate, net	86,166
Towers at Emeryville | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	223,697
Accumulated depreciation and amortization	(73,665)
Total real estate, net	150,032
3003 Washington Boulevard | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	154,814
Accumulated depreciation and amortization	(49,418)
Total real estate, net	105,396
Park Place Village | Office/Retail
Real Estate Properties [Line Items]
Total real estate held for investment, cost	87,836
Accumulated depreciation and amortization	(17,430)
Total real estate, net	70,406
201 17th Street | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	105,507
Accumulated depreciation and amortization	(37,952)
Total real estate, net	67,555
515 Congress | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	137,475
Accumulated depreciation and amortization	(40,512)
Total real estate, net	96,963
The Almaden | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	193,133
Accumulated depreciation and amortization	(56,081)
Total real estate, net	137,052
3001 Washington Boulevard | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	60,999
Accumulated depreciation and amortization	(16,648)
Total real estate, net	44,351
Carillon | Office Building
Real Estate Properties [Line Items]
Total real estate held for investment, cost	181,104
Accumulated depreciation and amortization	(49,165)
Total real estate, net	$ 131,939