Deferred Revenue and Acquisition-Related Intangible Liabilities, net - Estimated Amortization of Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
Total	$ 88,645	$ 96,271
Tenant funded tenant improvements [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenues amortized and recognized as rental income	22,500	$ 19,200	$ 18,400
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
2021	16,216
2022	15,188
2023	13,367
2024	11,325
2025	8,564
Thereafter	23,985
Total	$ 88,645