CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (129,039)	$ (724,857)
Other comprehensive income (loss):
Currency translation adjustments (CTA)	13,401	16,452
Reclassification of CTA to net loss	3,176	551
Derivative financial instruments:
Unrealized (gains) losses on derivative financial instruments	(1,367)
Income tax benefit	0
Unrealized (gains) losses on derivative financial instruments, net of taxes	(1,367)
Unrealized (gains) losses on derivative financial instruments		1,074
Income tax benefit		184
Unrealized (gains) losses on derivative financial instruments, net of taxes		890
Derivative financial instrument losses (gains) reclassified into net loss	202
Income tax expense	0
Reclassification adjustment for losses (gains) included in net loss, net of taxes	202
Derivative financial instrument losses (gains) reclassified into net loss		(1,623)
Income tax expense		(358)
Reclassification adjustment for losses (gains) included in net loss, net of taxes		(1,265)
Derivative financial instruments reclassified to advanced billings on contracts	(197)
Benefit obligations:
Unrealized losses on benefit obligations, net of taxes	0	(22)
Amortization of benefit plan benefits	(1,857)	(3,941)
Income tax benefit	0	1,630
Amortization of benefit plan benefits, net of taxes	(1,857)	(5,571)
Other	0	(38)
Other comprehensive income	13,358	10,997
Total comprehensive loss	(115,681)	(713,860)
Comprehensive loss (income) attributable to non-controlling interest	7,140	(229)
Comprehensive loss attributable to stockholders	$ (108,541)	$ (714,089)