Derivative Instruments, Gain (Loss) On Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Foreign exchange contracts- change in fair value	$ 157	$ 6	$ 71	$ (177)
Remeasurement of related contract receivables, billings in excess of revenue earned, and subcontractor accruals	158	(23)	84	42
(Loss) gain on derivative instruments, net	$ 315	$ (17)	$ 155	$ (135)