CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income including non-controlling interests	$ 64,252	$ 64,736	$ 203,622	$ 195,250
Other comprehensive income (loss), net of tax:
Unrealized loss on derivatives designated and qualifying as cash flow hedges, net of tax of $276 and $(55) in the three and nine months ended September 30, 2013; $147 and $148 in the three and nine months ended September 30, 2012	(734)	(5)	(147)	(564)
Defined benefit pension plan activity, net of tax of $2,050 and $8,232 in the three and nine months ended September 30, 2013; $2,755 and $8,593 in the three and nine months ended September 30, 2012	4,314	4,794	14,391	14,009
Currency translation adjustment	19,891	16,928	(15,209)	11,958
Other comprehensive income (loss):	23,471	21,717	(965)	25,403
Comprehensive income	87,723	86,453	202,657	220,653
Comprehensive (loss) income attributable to non-controlling interests	(1,678)	179	(1,769)	(389)
Comprehensive income attributable to shareholders	$ 89,401	$ 86,274	$ 204,426	$ 221,042