SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	$ 97,100,000
Initial Cost
Land	134,421,000
Building and Improvements	449,049,000
Net Improvements (Write-Offs) Since Acquisition	45,792,000
Gross Amount at Which Carried
Land	134,421,000
Building and Improvements	494,841,000
Investments in real estate	629,262,000	$ 1,344,636,000
Accumulated Depreciation	120,555,000	303,699,000	$ 271,055,000	$ 414,552,000
Other disclosures
Federal tax cost basis (unaudited)	661,503,000
Office | 3601 S Congress Avenue Austin, TX
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	9,569,000
Building and Improvements	18,593,000
Net Improvements (Write-Offs) Since Acquisition	9,833,000
Gross Amount at Which Carried
Land	9,569,000
Building and Improvements	28,426,000
Investments in real estate	37,995,000
Accumulated Depreciation	9,041,000
Office | 1 Kaiser Plaza Oakland, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	97,100,000
Initial Cost
Land	9,261,000
Building and Improvements	113,619,000
Net Improvements (Write-Offs) Since Acquisition	19,802,000
Gross Amount at Which Carried
Land	9,261,000
Building and Improvements	133,421,000
Investments in real estate	142,682,000
Accumulated Depreciation	44,659,000
Office | 2 Kaiser Plaza Parking Lot Oakland, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	10,931,000
Building and Improvements	110,000
Net Improvements (Write-Offs) Since Acquisition	1,735,000
Gross Amount at Which Carried
Land	10,931,000
Building and Improvements	1,845,000
Investments in real estate	12,776,000
Accumulated Depreciation	117,000
Office | 11600 Wilshire Blvd Los Angeles, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	3,477,000
Building and Improvements	18,522,000
Net Improvements (Write-Offs) Since Acquisition	2,304,000
Gross Amount at Which Carried
Land	3,477,000
Building and Improvements	20,826,000
Investments in real estate	24,303,000
Accumulated Depreciation	5,672,000
Office | 11620 Wilshire Blvd Los Angeles, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	7,672,000
Building and Improvements	51,999,000
Net Improvements (Write-Offs) Since Acquisition	7,242,000
Gross Amount at Which Carried
Land	7,672,000
Building and Improvements	59,241,000
Investments in real estate	66,913,000
Accumulated Depreciation	15,731,000
Office | 4750 Wilshire Blvd Los Angeles, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	16,633,000
Building and Improvements	28,985,000
Net Improvements (Write-Offs) Since Acquisition	3,897,000
Gross Amount at Which Carried
Land	16,633,000
Building and Improvements	32,882,000
Investments in real estate	49,515,000
Accumulated Depreciation	4,170,000
Office | Lindblade Media Center Los Angeles, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	6,342,000
Building and Improvements	11,568,000
Net Improvements (Write-Offs) Since Acquisition	24,000
Gross Amount at Which Carried
Land	6,342,000
Building and Improvements	11,592,000
Investments in real estate	17,934,000
Accumulated Depreciation	1,480,000
Office | 1130 Howard Street San Francisco, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	8,290,000
Building and Improvements	10,480,000
Net Improvements (Write-Offs) Since Acquisition	5,000
Gross Amount at Which Carried
Land	8,290,000
Building and Improvements	10,485,000
Investments in real estate	18,775,000
Accumulated Depreciation	638,000
Office | 9460 Wilshire Boulevard Los Angeles, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	52,199,000
Building and Improvements	76,730,000
Net Improvements (Write-Offs) Since Acquisition	620,000
Gross Amount at Which Carried
Land	52,199,000
Building and Improvements	77,350,000
Investments in real estate	129,549,000
Accumulated Depreciation	4,644,000
Hotel | Sheraton Grand Hotel Sacramento, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	3,497,000
Building and Improvements	107,447,000
Net Improvements (Write-Offs) Since Acquisition	122,000
Gross Amount at Which Carried
Land	3,497,000
Building and Improvements	107,569,000
Investments in real estate	111,066,000
Accumulated Depreciation	31,158,000
Hotel | Sheraton Grand Hotel Parking & Retail Sacramento, CA
SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION
Encumbrances	0
Initial Cost
Land	6,550,000
Building and Improvements	10,996,000
Net Improvements (Write-Offs) Since Acquisition	208,000
Gross Amount at Which Carried
Land	6,550,000
Building and Improvements	11,204,000
Investments in real estate	17,754,000
Accumulated Depreciation	3,245,000
Line of Credit | Revolving Credit Facility
Other disclosures
Outstanding balance	$ 153,000,000	$ 130,000,000