Schedule III - Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) ft² property project
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances \| $	$ 254,365
Rentable square feet	14,620,166
Investment in real estate, federal Income tax basis \| $	$ 8,600,000
In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings \| project	3
Rentable square feet	856,000
Sunset Blvd., Gower St. and El Centro Ave. Properties in Los Angeles [Member]
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings \| property	6
1550 N. El Centro Avenue, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Number of Units \| property	200
Rentable square feet	0
3200 Paseo Village Way, San Diego, CA (Resi Phase I) (16) [Member]
Real Estate and Accumulated Depreciation [Line Items]
Number of Units \| property	608
333 Dexter Ave. North, South Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Rentable square feet	0
Office Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Unamortized debt issuance expense \| $	$ (800)
Office Building [Member] \| Sunset Blvd., Gower St. and El Centro Ave. Properties in Los Angeles [Member]
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings \| property	5
Office Building [Member] \| W. Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances \| $	$ 166,776
Office Building [Member] \| 320 Westlake Ave. North, WA and 321 Terry Avenue North, Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances \| $	$ 87,589
Residential Tower [Member] \| Sunset Blvd., Gower St. and El Centro Ave. Properties in Los Angeles [Member]
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings \| property	1
Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Tenant Improvements [Member] \| Office Building [Member] \| 12860 and 12830 El Camino Real, Del Mar, CA [Member] \| In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet	285,000
Tenant Improvements [Member] \| Office Building [Member] \| 333 Dexter Ave. North, South Lake Union, WA [Member] \| In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet	635,000
Tenant Improvements [Member] \| Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	1 year
Tenant Improvements [Member] \| Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	20 years

Amount of lien or mortgage outstanding on real estate investment properties for entities with a substantial portion of business acquiring and holding investment real estate.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column B
-Subsection 28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28(Column B))
-URI http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024

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Cost basis of real estate investments for federal income tax purposes for entities with a substantial portion of business acquiring and holding investment real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Footnote 6
-Subsection 28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28(Footnote 6))
-URI http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024

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Net rentable area for properties owned.

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The number of real estate properties owned as of the balance sheet date.

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The number of units in a real estate property owned as of the balance sheet date.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Useful life on which depreciation was computed for entities with a substantial portion of business acquiring and holding investment real estate, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-28(Column I))
-URI http://asc.fasb.org/extlink&oid=120402810&loc=d3e638233-123024

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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