Operating Leases - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) property state	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessor, Lease, Description [Line Items]
Number of properties owned	6,592
Number of U.S. states where properties are owned (states) | state	49
Percentage rent received | $	$ 5.1	$ 8.0	$ 5.9
Single-client properties
Lessor, Lease, Description [Line Items]
Number of properties owned	6,555
Single-client properties as percentage of total properties (as a percent)	99.40%
Properties available for lease or sale
Lessor, Lease, Description [Line Items]
Number of properties owned	140