CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 25,532	$ 16,065	$ 73,460		$ 36,370
Foreign currency translation adjustment	6,407	1,408	23,136		6,605
Derivative instruments designated as cash flow hedges:
Unrealized gain (loss) on derivative instruments held at period end, net of tax (Note 6)	(51)		(487)
Unrealized (gain) loss reclassified into earnings (Note 6)	115	0	222		11
Accumulated other comprehensive income (loss) pension and post-retirement benefits:
Actuarial net gain (loss) incurred in fiscal year, net of tax (Note 6)	(300)	0	35		0
Pension and postretirement benefit plans reclassified into earnings, net of tax (Note 6):
Amortization of loss, net of tax (Note 6)	0	34	36		105
Other comprehensive income	6,171	1,442	22,942	[1]	6,721	[2]
Comprehensive income	$ 31,703	$ 17,507	$ 96,402		$ 43,091

[1] Net of taxes of $38 and $(151) for the pension plans and postretirement benefits and unrealized gain (loss) on derivatives, respectively.

[2] Net of taxes of $58 and $5 for the pension plans and postretirement benefits and unrealized gain (loss) on derivatives, respectively.