Operating Leases (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lessor, Lease, Description [Line Items]
Operating Leases, Variable Rental Revenue			$ 31,200,000	$ 29,200,000
Contract with Customer, Liability, Revenue Recognized	$ 2,800,000	$ 2,800,000
2020			827,000
2021			3,302,000
2022			3,055,000
2023			2,606,000
2024			3,229,000
Thereafter			4,299,000
Lessee, Operating Lease, Liability, Payments, Due, Total			17,318,000
Rental Revenue
Lessor, Lease, Description [Line Items]
Contract with Customer, Liability, Revenue Recognized			330,400,000	$ 290,000,000.0
Office Space
Lessor, Lease, Description [Line Items]
2020			723,000
2021			2,930,000
2022			2,855,000
2023			2,497,000
2024			3,139,000
Thereafter			3,163,000
Lessee, Operating Lease, Liability, Payments, Due, Total			15,307,000
Ground Leases
Lessor, Lease, Description [Line Items]
2020			13,000
2021			51,000
2022			51,000
2023			51,000
2024			51,000
Thereafter			1,136,000
Lessee, Operating Lease, Liability, Payments, Due, Total			1,353,000
Office Equipment
Lessor, Lease, Description [Line Items]
2020			91,000
2021			321,000
2022			149,000
2023			58,000
2024			39,000
Thereafter			0
Lessee, Operating Lease, Liability, Payments, Due, Total			$ 658,000