Management Agreements and Leases - Other, Net Lease Portfolio and TA Leases (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) ft² tenant brand hotel industry property agreement travelCenter travel_center	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) ft² tenant brand hotel industry property agreement travelCenter travel_center	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Management Agreements and Leases [Line Items]
Cash (used in) provided by operating activities			$ 1,002	$ 65,524
Number of operating agreements | agreement	6		6
Rental income	$ 98,724	$ 96,776	$ 286,742	294,633
Adjustments necessary to record rent on straight line basis	905	2,370	$ 3,087	298
COVID-19
Management Agreements and Leases [Line Items]
Deferred rent agreement	$ 2,852
Number of newly entered deferred rent agreements | tenant	1,000		1,000
Amount of deferred annual minimum rents			$ 10,827
Number of rent deferral agreements | tenant	15		15
Temporary rent assistance as a percentage of total rental income			2.90%
Reserves for uncollectible amounts against rental income	$ 5,373	2,369	$ 588	7,689
Reserves for uncollectible rents	16,434		$ 16,434		$ 18,230
COVID-19 | Minimum
Management Agreements and Leases [Line Items]
Deferred rent repayment period			12 months
COVID-19 | Maximum
Management Agreements and Leases [Line Items]
Deferred rent repayment period			24 months
TA
Management Agreements and Leases [Line Items]
Deferred percentage rental income	$ 1,849	893	$ 4,827	1,742
Hotel
Management Agreements and Leases [Line Items]
Number of properties owned | hotel	304		304
Number of operating agreements | agreement	6		6
Hotel | InterContinental Hotels Group, plc
Management Agreements and Leases [Line Items]
Number of properties owned | hotel	103		103
Hotel | Maximum
Management Agreements and Leases [Line Items]
Number of properties owned | hotel	208		208
Hotel | IHG Agreement
Management Agreements and Leases [Line Items]
Number of properties owned | hotel	1		1
Cash (used in) provided by operating activities	$ 962		$ (384)
Realized returns and rents		9,654		117,874
Net Lease Property
Management Agreements and Leases [Line Items]
Number of properties owned | property	794		794
Square feet | ft²	13,574,656		13,574,656
Operating agreement annual rent and return			$ 370,945
Weighted average remaining lease term	10 years 3 months 18 days		10 years 3 months 18 days
Percentage of portfolio leased by tenants	98.20%		98.20%
Number of tenants | tenant	175		175
Number of brands | brand	134		134
Number of industries | industry	21		21
Travel centers
Management Agreements and Leases [Line Items]
Number of properties owned | travelCenter	179		179
Travel centers | Travel Centers of America
Management Agreements and Leases [Line Items]
Number of properties owned | travel_center	179		179
Operating agreement annual rent and return			$ 246,111
Quarterly payments to deferred rent receivable	$ 4,404	4,404	13,212	13,212
Remaining balance of previously deferred rents	26,420		26,420		39,632
Rental income	62,116	61,528	186,357	184,583
Adjustments necessary to record rent on straight line basis	(3,267)	(3,250)	(9,789)	(9,834)
Accruals for unpaid rent, including deferred rent	$ 46,660		$ 46,660		$ 55,530
Deferred rent receivable from TA agreement, during the period		$ 893		$ 1,742
Increase in annual rent fixed interest rate			8.50%
Travel centers | Travel Centers of America | Real Estate Assets | Customer concentration risk
Management Agreements and Leases [Line Items]
Percentage of total annual minimum rents			26.70%
Travel centers | Travel Centers of America | TA agreements
Management Agreements and Leases [Line Items]
Number of operating agreements | agreement	5		5