REAL ESTATE - Schedule of Real Estate Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Real Estate Properties [Line Items]
Total real estate held for investment, cost	$ 2,249,002	$ 2,244,923
Accumulated depreciation and amortization	(704,304)	(681,392)
Total real estate, net	1,544,698	$ 1,563,531
Town Center \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	144,104
Accumulated depreciation and amortization	(60,137)
Total real estate, net	83,967
Gateway Tech Center \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	37,398
Accumulated depreciation and amortization	(14,575)
Total real estate, net	22,823
60 South Sixth \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	115,520
Accumulated depreciation and amortization	(3,644)
Total real estate, net	111,876
Sterling Plaza \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	98,234
Accumulated depreciation and amortization	(37,118)
Total real estate, net	61,116
Accenture Tower \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	576,067
Accumulated depreciation and amortization	(190,635)
Total real estate, net	385,432
Ten Almaden \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	131,599
Accumulated depreciation and amortization	(46,605)
Total real estate, net	84,994
Towers at Emeryville \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	223,725
Accumulated depreciation and amortization	(75,925)
Total real estate, net	147,800
3003 Washington Boulevard \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	154,926
Accumulated depreciation and amortization	(50,700)
Total real estate, net	104,226
Park Place Village \| Office/Retail
Real Estate Properties [Line Items]
Total real estate held for investment, cost	88,028
Accumulated depreciation and amortization	(18,506)
Total real estate, net	69,522
201 17th Street \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	105,538
Accumulated depreciation and amortization	(39,042)
Total real estate, net	66,496
515 Congress \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	138,040
Accumulated depreciation and amortization	(41,839)
Total real estate, net	96,201
The Almaden \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	192,549
Accumulated depreciation and amortization	(57,392)
Total real estate, net	135,157
3001 Washington Boulevard \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	60,999
Accumulated depreciation and amortization	(17,123)
Total real estate, net	43,876
Carillon \| Office
Real Estate Properties [Line Items]
Total real estate held for investment, cost	182,275
Accumulated depreciation and amortization	(51,063)
Total real estate, net	$ 131,212

The cumulative amount of depreciation for real estate property held for investment purposes.

Name:	us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

Name:	us-gaap_RealEstateInvestmentPropertyAtCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

Name:	us-gaap_RealEstateInvestmentPropertyNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RealEstatePropertiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration