Revenue Recognition - 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]
Lease revenues	$ 41,394	$ 55,267	$ 137,479	$ 163,597
Rental revenues	43,499	57,760	143,087	170,470
Parking revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,106	1,366	3,046	4,222
Tenant services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 999	$ 1,127	$ 2,562	$ 2,651