Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Defined Benefit Plan Disclosure
Number of defined benefit pension plans			2
Components of net periodic benefit cost:
Cash contributions to the Plan	$ 2,300		$ 20,000
Contributions to U.S defined contribution plans by the Company, maximum percentage of eligible compensation (as a percent)			5.00%
Matching contributions to U.S defined contribution plans by the Company			1,859	1,585
Pension Benefits
Components of net periodic benefit cost:
Service cost	2,183	1,439	5,150	4,333
Interest cost	6,182	5,661	16,573	17,002
Expected return on plan assets	(7,399)	(5,643)	(17,852)	(16,917)
Amortization of transition obligation	(28)	(27)	(84)	(81)
Amortization of prior service cost	676	38	1,666	1,814
Amortization of net actuarial losses	3,209	2,631	9,099	7,889
Net pension expense	4,823	4,099	14,552	14,040
Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost	50	41	150	124
Interest cost	212	197	636	590
Amortization of transition obligation	16	16	47	47
Amortization of net actuarial losses	325	221	976	663
Net pension expense	$ 603	$ 475	$ 1,809	$ 1,424