Accrual for Loss Contracts Related to Service (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accrual For Loss Contract Related to Service
Beginning balance		$ 752	$ 10,050
Change in estimate	$ (1,071)		(1,071)
Reduction for losses realized		$ (752)	(3,559)
Ending balance	$ 5,420		$ 5,420