Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 11,753	$ (48,180)	$ 38,436	$ (104,028)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	964	46,319	(38,504)	51,714
Interest rate swaps – net change in deferred gain or loss	350	1,302	14,148	(3,396)
Pension plans – net change in deferred actuarial loss	53	52	164	149
Other comprehensive income (loss), net of tax	1,367	47,673	(24,192)	48,467
Comprehensive income (loss)	$ 13,120	$ (507)	$ 14,244	$ (55,561)