Fair Values of Assets and Liabilities Reconciliation of Level 3 Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 12,276	$ 20,970
Total (gains) losses—realized/unrealized:
Net revaluations of notes payable associated with structured financings, at fair value	(706)	(1,165)
Repayments on outstanding notes payable, net	(439)	(1,736)
Ending Balance	$ 11,131	$ 18,069