Basis of Presentation - Narratives (Details) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) vie	Jun. 30, 2020 USD ($) vie	Dec. 31, 2019 USD ($) vie	Dec. 31, 2018	Jan. 01, 2020 USD ($)
Variable Interest Entity
Variable interest entities, count | vie	19	19	19
Variable interest entities consolidated, count | vie	18	18	18
Variable interest entities unconsolidated, count | vie	1	1	1
Uncollected rent receivable	$ 3,000	$ 3,000
Accounts receivable written off during the period		2,800
Deferred tax liabilities	45,600	45,600	$ 48,600
Deferred tax assets, net of valuation	1,400	1,400	1,400
Adjustments to retained earnings	518,253	$ 518,253	$ 470,326
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201602Member
Cumulative Effect, Period of Adoption, Adjustments
Variable Interest Entity
Adjustments to retained earnings					$ (6,900)
Equity method investments
Variable Interest Entity
Equity investment in real estate	13,800	$ 13,800	$ 14,900
Lease revenues — net-leased
Variable Interest Entity
Uncollected rent receivable	$ 400	400
Accounts receivable written off during the period		$ 7,000