CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income including non-controlling interests	$ 198,373	$ 127,412	$ 253,880
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges, net of tax of $(21) in 2016; $336 in 2015; $(121) in 2014	39	557	(378)
Defined pension plan activity, net of tax of $4,297 in 2016, $61,538 in 2015; $(20,951) in 2014	3,837	98,117	(37,200)
Currency translation adjustment	(36,752)	(106,935)	(98,365)
Transactions with non-controlling interests	0	(7)	(4)
Other comprehensive income (loss)	(32,876)	(8,268)	(135,947)
Comprehensive income	165,497	119,144	117,933
Comprehensive (loss) income attributable to non-controlling interests	(132)	(689)	(72)
Comprehensive income attributable to shareholders	165,629	119,833	118,005
Accumulated Other Comprehensive Income (Loss) [Member]
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges, net of tax of $(21) in 2016; $336 in 2015; $(121) in 2014	39	557	(378)
Defined pension plan activity, net of tax of $4,297 in 2016, $61,538 in 2015; $(20,951) in 2014	3,837	98,117	(37,200)
Currency translation adjustment	$ (36,646)	$ (106,312)	$ (99,099)