Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Comprehensive Income
Net income	$ 50,182	$ 40,398	$ 98,133	$ 77,023
Unrealized gains on derivatives, net of tax	860	(15,571)	1,764	(13,996)
Pension and other post-retirement plans, net of tax	792	(3)	1,577	740
Cumulative translation adjustment	6,659	(28,224)	31,537	(50,865)
Comprehensive income	$ 58,493	$ (3,400)	$ 133,011	$ 12,902