CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income including non-controlling interests	$ 293,083	$ 286,993	$ 247,475
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges, net of tax of $(58) in 2019; $346 in 2018; $17 in 2017	(68)	819	288
Defined pension plan activity, net of tax of $4,188 in 2019, $1,691 in 2018; $19,252 in 2017	11,503	3,228	10,662
Currency translation adjustment	6,735	(50,693)	71,016
Other comprehensive income (loss)	18,170	(46,646)	81,966
Comprehensive income	311,253	240,347	329,441
Comprehensive (loss) income attributable to non-controlling interests	255	(166)	87
Comprehensive income attributable to shareholders	310,998	240,513	329,354
Accumulated Other Comprehensive Income (Loss) [Member]
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges, net of tax of $(58) in 2019; $346 in 2018; $17 in 2017	(68)	819	288
Defined pension plan activity, net of tax of $4,188 in 2019, $1,691 in 2018; $19,252 in 2017	11,503	3,228	10,662
Currency translation adjustment	$ 6,454	$ (50,600)	$ 70,901