Notes Receivable and Current Expected Credit Losses (Amortized Cost Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	$ 168,716	$ 159,371
Mezzanine Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	0
2019	0
2018	111,611
2017	14,723
2016	42,368
Total notes receivable	168,702
Pass | Mezzanine Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	0
2019	0
2018	111,611
2017	0
2016	0
Total notes receivable	111,611
Special Mention | Mezzanine Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Total notes receivable	0
Substandard | Mezzanine Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
2020	0
2019	0
2018	0
2017	14,723
2016	42,368
Total notes receivable	$ 57,091