Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from customers	$ 8,065	$ 11,629	$ 41,012	$ 36,450
Revenues	8,377	12,014	41,904	37,474
Land sales
Disaggregation of Revenue [Line Items]
Revenue from customers	44	238	17,090	769
Management services
Disaggregation of Revenue [Line Items]
Revenue from customers	7,999	11,458	22,557	33,689
Operating properties
Disaggregation of Revenue [Line Items]
Revenue from customers	22	(67)	1,365	1,992
Operating properties leasing revenues	312	385	892	1,024
Revenues	334	318	2,257	3,016
Valencia
Disaggregation of Revenue [Line Items]
Revenue from customers	(72)	(234)	18,005	1,562
Revenues	240	151	18,897	2,586
Valencia | Land sales
Disaggregation of Revenue [Line Items]
Revenue from customers	44	17	17,090	105
Valencia | Management services
Disaggregation of Revenue [Line Items]
Revenue from customers	0	0	0	0
Valencia | Operating properties
Disaggregation of Revenue [Line Items]
Revenue from customers	(116)	(251)	915	1,457
Operating properties leasing revenues	312	385	892	1,024
San Francisco
Disaggregation of Revenue [Line Items]
Revenue from customers	138	950	1,285	3,015
Revenues	138	950	1,285	3,015
San Francisco | Land sales
Disaggregation of Revenue [Line Items]
Revenue from customers	0	221	0	664
San Francisco | Management services
Disaggregation of Revenue [Line Items]
Revenue from customers	0	545	835	1,816
San Francisco | Operating properties
Disaggregation of Revenue [Line Items]
Revenue from customers	138	184	450	535
Operating properties leasing revenues	0	0	0	0
Great Park
Disaggregation of Revenue [Line Items]
Revenue from customers	7,895	10,814	21,424	31,647
Revenues	7,895	10,814	21,424	31,647
Great Park | Land sales
Disaggregation of Revenue [Line Items]
Revenue from customers	0	0	0	0
Great Park | Management services
Disaggregation of Revenue [Line Items]
Revenue from customers	7,895	10,814	21,424	31,647
Great Park | Operating properties
Disaggregation of Revenue [Line Items]
Revenue from customers	0	0	0	0
Operating properties leasing revenues	0	0	0	0
Commercial
Disaggregation of Revenue [Line Items]
Revenue from customers	104	99	298	226
Revenues	104	99	298	226
Commercial | Land sales
Disaggregation of Revenue [Line Items]
Revenue from customers	0	0	0	0
Commercial | Management services
Disaggregation of Revenue [Line Items]
Revenue from customers	104	99	298	226
Commercial | Operating properties
Disaggregation of Revenue [Line Items]
Revenue from customers	0	0	0	0
Operating properties leasing revenues	$ 0	$ 0	$ 0	$ 0