Pensions and Other Postretirement Benefits (Components of net periodic benefit cost and changes recognized in other comprehensive income) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost/(Credit):
Service cost	$ 276	$ 333	$ 978	$ 2,538
Interest cost	14,287	15,268	45,212	45,662
Expected return on plan assets	(17,167)	(15,520)	(53,138)	(46,088)
Amortization of net actuarial loss/(gain)	3,522	3,542	10,477	12,806
Amortization of prior service (credit)/cost	(539)	8	(521)	(408)
Amortization of transition (asset)/obligation	12	(13)	35	35
(Curtailment gain)/settlement charges	0	0	0	(19,665)	[1]
Net periodic benefit cost/(credit)	391	3,618	3,043	(5,120)
Changes recognized in other comprehensive income:
Net actuarial loss	0	675	3,597	21,805
Prior service credit	0	0	(48,056)	(9,054)
Amortization of net actuarial (loss)/gain	(3,522)	(3,542)	(10,477)	(12,806)
Amortization of prior service (cost)/credit	539	(8)	521	408
Amortization of (obligation)/asset	(12)	13	(35)	(35)
Total recognized in other comprehensive income - before tax	(2,995)	(2,862)	(54,450)	318
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost/(Credit):
Service cost	23	27	70	82
Interest cost	824	913	2,471	2,739
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss/(gain)	35	7	106	36
Amortization of prior service (credit)/cost	(891)	(1,002)	(2,673)	(2,987)
Amortization of transition (asset)/obligation	0	8	0	0
(Curtailment gain)/settlement charges	0	0	0	0
Net periodic benefit cost/(credit)	(9)	(47)	(26)	(130)
Changes recognized in other comprehensive income:
Net actuarial loss	0	0	0	0
Prior service credit	0	0	0	0
Amortization of net actuarial (loss)/gain	(35)	(7)	(106)	(36)
Amortization of prior service (cost)/credit	891	1,002	2,673	2,987
Amortization of (obligation)/asset	0	(8)	0	0
Total recognized in other comprehensive income - before tax	$ 856	$ 987	$ 2,567	$ 2,951

[1] During the nine months ended September 30, 2010, a curtailment gain resulted from the closure of the U.K. pension plan for future benefit accrual. During the nine months ended September 30, 2010, a charge was incurred related to the settlement of pension obligations with former employees of the Canada pension plan.