Notes Receivable and Allowance for Losses Schedule Of Notes Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	$ 97,677	$ 95,529
Allowance for losses on non-impaired loans	1,647	1,647
Allowance for losses on receivables specifically evaluated for impairment	490	490
Total loan reserves	2,137	2,137
Net carrying value	95,540	93,392
Current portion, net	17,254	13,256
Long-term portion, net	78,286	80,136
Senior
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	73,643	73,700
Subordinated
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	20,975	18,647
Unsecured
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	$ 3,059	$ 3,182