Finance Receivables - Internal Credit Quality Rating (Details)
$ in Thousands
Dec. 31, 2016
USD ($)
tenant
Dec. 31, 2015
USD ($)
tenant
Credit Quality Of Finanace Receivables:    
Financing receivable $ 539,892 $ 539,608
Direct Financing Method | Internally Assigned Grade 1    
Credit Quality Of Finanace Receivables:    
Number of tenants and obligors | tenant 0 0
Financing receivable $ 0 $ 0
Direct Financing Method | Internally Assigned Grade 2    
Credit Quality Of Finanace Receivables:    
Number of tenants and obligors | tenant 2 1
Financing receivable $ 61,949 $ 2,264
Direct Financing Method | Internally Assigned Grade 3    
Credit Quality Of Finanace Receivables:    
Number of tenants and obligors | tenant 9 10
Financing receivable $ 412,075 $ 429,212
Direct Financing Method | Internally Assigned Grade 4    
Credit Quality Of Finanace Receivables:    
Number of tenants and obligors | tenant 5 4
Financing receivable $ 65,868 $ 108,132
Direct Financing Method | Internally Assigned Grade 5    
Credit Quality Of Finanace Receivables:    
Number of tenants and obligors | tenant 0 0
Financing receivable $ 0 $ 0