Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 295,278		$ 303,301	$ 873,457	$ 932,369
COVID-19 [Member]
Segment Reporting Information [Line Items]
Deferral agreements	3,900			16,700
Straight-line rent	5,700			5,700
Rental Revenue [Member]
Segment Reporting Information [Line Items]
Reduction of revenue	9,600			28,200
General reserve increase	5,100			6,600
Not probable for collection	4,800			14,300
Straight line rent receivable, deemed collectible	300
Straight line rent receivable, receivable				7,300
COVID-19 effect	10,200			18,600
COVID-19 effect, general reserve increase	5,100			6,000
COVID-19 effect, amount not probable For collection	4,100			7,900
COVID-19 effect, straight line rent receivable, increase in reserve	1,000			4,700
Total revenues	293,692		302,985	870,854	931,871
Rental Revenue [Member] | COVID-19 [Member]
Segment Reporting Information [Line Items]
Deferral agreements, abated	6,500			17,700
Straight line rent, lease amendments	800			12,000
Rental Revenue [Member] | Lease Executed Through September 30,2020 [Member] | COVID-19 [Member]
Segment Reporting Information [Line Items]
Deferral agreements, abated	5,900
Rental Revenue [Member] | Lease Executed From July 1, 2020 Through September 30, 2020 [Member] | COVID-19 [Member]
Segment Reporting Information [Line Items]
Deferral agreements, abated		$ 600
Fees From Managed Partnership [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 1,586		$ 316	$ 2,603	$ 498