CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income including non-controlling interests	$ 72,527	$ 66,365	$ 139,370	$ 130,514
Other comprehensive (loss) income, net of tax:
Unrealized (loss) gain on derivatives designated and qualifying as cash flow hedges, net of tax of $(217) and $(331) in the three and six months ended June 30, 2013; $(74) and $1 in the three and six months ended June 30, 2012	(15)	(61)	587	(559)
Defined benefit pension plan activity, net of tax of $3,114 and $6,182 in the three and six months ended June 30, 2013; $2,994 and $5,838 in the three and six months ended June 30, 2012	4,972	4,369	10,077	9,215
Currency translation adjustment	(20,861)	(30,533)	(35,100)	(4,970)
Other comprehensive (loss) income:	(15,904)	(26,225)	(24,436)	3,686
Comprehensive income	56,623	40,140	114,934	134,200
Comprehensive loss attributable to non-controlling interests	(241)	(543)	(91)	(568)
Comprehensive income attributable to shareholders	$ 56,864	$ 40,683	$ 115,025	$ 134,768