Summary of Significant Accounting Policies - Segment and Geographic Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | segment									1
Number of reportable segments | segment									1
Total operating revenues	$ 787,463	$ 806,466	$ 800,797	$ 814,515	$ 778,267	$ 768,924	$ 754,919	$ 744,368	$ 3,209,241	$ 3,046,478	$ 2,457,928
Net investments in real estate	15,517,684				15,079,726				$ 15,517,684	$ 15,079,726
Geographic Concentration Risk | Sales
Summary Of Significant Accounting Policies [Line Items]
Concentration risk									9.00%	9.70%	11.20%
Geographic Concentration Risk | Total long-lived assets
Summary Of Significant Accounting Policies [Line Items]
Concentration risk									12.00%	10.90%	12.10%
Outside the United States
Summary Of Significant Accounting Policies [Line Items]
Total operating revenues									$ 627,400	$ 564,400	$ 515,200
Net investments in real estate	3,700,000				3,800,000				3,700,000	3,800,000	3,100,000
United States
Summary Of Significant Accounting Policies [Line Items]
Total operating revenues									2,600,000	2,500,000	1,900,000
Net investments in real estate	10,600,000				11,100,000				10,600,000	11,100,000	10,500,000
United Kingdom
Summary Of Significant Accounting Policies [Line Items]
Total operating revenues									288,200	295,300	275,100
Net investments in real estate	$ 1,700,000				$ 1,600,000				$ 1,700,000	$ 1,600,000	$ 1,700,000