Cash flow information (Details 14) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property, plant and equipment [Line Items]
Interest paid, net	$ 74,378	$ 78,133	$ 80,962
Income taxes paid, net	3,277	(12,287)	46,892
Capital expenditures incurred but not yet paid	$ 76,205	$ 41,540	$ 30,895