Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (437,012)	$ 72,793	$ 108,787
Other comprehensive income (loss), net of tax:
Currency translation adjustments (net of income tax of $0 in 2018, 2017 and 2016)	(19,366)	43,060	(15,017)
Change in unrecognized net periodic pension costs (net of income tax of $1,377 in 2018, $6 in 2017, and $343 in 2016)	3,920	(857)	(727)
Net unrealized gain (loss) on derivative instruments and other (net of income tax of $1,831 in 2018, and $0 in 2017 and 2016)	(5,082)	196	86
Other comprehensive income (loss)	(20,528)	42,399	(15,658)
Comprehensive income (loss)	$ (457,540)	$ 115,192	$ 93,129