Guarantees - Changes from credit recourses agreements (Details) - Financial Guarantee - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Guarantor Obligations [Line Items]
Balance as of beginning of period	$ 48,100	$ 57,425	$ 56,230	$ 58,820
Provision for recourse liability	2,755	3,000	3,711	5,991
Net charge-offs	(5,394)	(2,678)	(14,480)	(7,064)
Balance as of end of period	$ 45,461	$ 57,747	$ 45,461	$ 57,747