CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 34,555	$ (56,990)	$ (15,313)	$ (134,497)
Other comprehensive income (loss):
Currency translation adjustments (CTA)	(22,916)	21,433	(24,631)	23,714
Reclassification of CTA to net loss	0	0	0	3,176
Derivative financial instruments:
Unrealized losses on derivative financial instruments	0	0	0	(1,367)
Derivative financial instrument (losses) gains reclassified into net loss	0	0	0	202
Derivative financial instruments reclassified to advanced billings on contracts	0	(197)	0	(197)
Benefit obligations:
Amortization of benefit plan benefits	(246)	(515)	(738)	(1,385)
Other comprehensive (loss) income	(23,162)	20,721	(25,369)	24,143
Total comprehensive loss	11,393	(36,269)	(40,682)	(110,354)
Comprehensive (loss) income attributable to non-controlling interest	175	(88)	434	341
Comprehensive income (loss) attributable to stockholders	$ 11,568	$ (36,357)	$ (40,248)	$ (110,013)