Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 item	Sep. 30, 2011
Components of net periodic benefit cost:
Contributions to U.S defined contribution plans by the Company, maximum percentage of eligible compensation			5.00%
Matching contributions to U.S defined contribution plans by the Company			$ 2,100	$ 1,900
Pension Benefits
Defined Benefit Plan Disclosure
Number of U.S. defined benefit pension plans			2
Components of net periodic benefit cost:
Service cost	1,911	2,183	5,795	5,150
Interest cost	5,387	6,182	16,340	16,573
Expected return on plan assets	(6,089)	(7,399)	(18,408)	(17,852)
Amortization of transition obligation	(27)	(28)	(81)	(84)
Amortization of prior service cost	535	676	1,610	1,666
Amortization of net actuarial losses	4,484	3,209	13,592	9,099
Net pension expense	6,201	4,823	18,848	14,552
U.S. plans, Pension Benefits
Components of net periodic benefit cost:
Employer contributions	5,600		18,500
Estimated cash contribution to the Plans in 2012 based on current actuarial calculations	23,000		23,000
Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost	45	50	134	150
Interest cost	169	212	508	636
Amortization of transition obligation	16	16	47	47
Amortization of net actuarial losses	242	325	725	976
Net pension expense	$ 472	$ 603	$ 1,414	$ 1,809