Deferred Revenue and Acquisition-Related Intangible Liabilities, net - Estimated Amortization of Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
Total	$ 96,271	$ 104,558
Tenant funded tenant improvements [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenues amortized and recognized as rental income	19,200	$ 18,400	$ 16,800
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
2020	16,935
2021	15,426
2022	14,320
2023	12,553
2024	10,318
Thereafter	26,719
Total	$ 96,271