Finance Receivables - Internal Credit Quality Rating (Details) $ in Thousands	Jun. 30, 2017 USD ($) tenant	Dec. 31, 2016 USD ($) tenant
Credit Quality Of Finance Receivables
Carrying Value	$ 105,715	$ 116,096
Internally Assigned Grade 1
Credit Quality Of Finance Receivables
Number of tenants and obligors | tenant	0	1
Carrying Value	$ 0	$ 10,516
Internally Assigned Grade 2
Credit Quality Of Finance Receivables
Number of tenants and obligors | tenant	1	1
Carrying Value	$ 9,193	$ 9,154
Internally Assigned Grade 3
Credit Quality Of Finance Receivables
Number of tenants and obligors | tenant	2	2
Carrying Value	$ 29,698	$ 29,679
Internally Assigned Grade 4
Credit Quality Of Finance Receivables
Number of tenants and obligors | tenant	3	3
Carrying Value	$ 66,824	$ 66,747
Internally Assigned Grade 5
Credit Quality Of Finance Receivables
Number of tenants and obligors | tenant	0	0
Carrying Value	$ 0	$ 0