REAL ESTATE - Schedule of Real Estate Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Real Estate Properties [Line Items]
Total real estate at, cost	$ 1,816,867	$ 1,823,531
Accumulated depreciation and amortization	(559,392)	(543,443)
Total real estate held for investment, net	1,257,475	$ 1,280,088
Town Center | Office
Real Estate Properties [Line Items]
Total real estate at, cost	149,202
Accumulated depreciation and amortization	(66,946)
Total real estate held for investment, net	82,256
60 South Sixth | Office
Real Estate Properties [Line Items]
Total real estate at, cost	88,240
Accumulated depreciation and amortization	(2,899)
Total real estate held for investment, net	85,341
Accenture Tower | Office
Real Estate Properties [Line Items]
Total real estate at, cost	583,978
Accumulated depreciation and amortization	(213,795)
Total real estate held for investment, net	370,183
Ten Almaden | Office
Real Estate Properties [Line Items]
Total real estate at, cost	131,814
Accumulated depreciation and amortization	(51,141)
Total real estate held for investment, net	80,673
Towers at Emeryville | Office
Real Estate Properties [Line Items]
Total real estate at, cost	130,272
Accumulated depreciation and amortization	(2,654)
Total real estate held for investment, net	127,618
3003 Washington Boulevard | Office
Real Estate Properties [Line Items]
Total real estate at, cost	154,914
Accumulated depreciation and amortization	(54,916)
Total real estate held for investment, net	99,998
201 17th Street | Office
Real Estate Properties [Line Items]
Total real estate at, cost	105,896
Accumulated depreciation and amortization	(43,404)
Total real estate held for investment, net	62,492
515 Congress | Office
Real Estate Properties [Line Items]
Total real estate at, cost	139,225
Accumulated depreciation and amortization	(46,951)
Total real estate held for investment, net	92,274
The Almaden | Office
Real Estate Properties [Line Items]
Total real estate at, cost	90,201
Accumulated depreciation and amortization	0
Total real estate held for investment, net	90,201
3001 Washington Boulevard | Office
Real Estate Properties [Line Items]
Total real estate at, cost	61,070
Accumulated depreciation and amortization	(18,963)
Total real estate held for investment, net	42,107
Carillon | Office
Real Estate Properties [Line Items]
Total real estate at, cost	182,055
Accumulated depreciation and amortization	(57,723)
Total real estate held for investment, net	$ 124,332