Pensions and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Pension Benefits [Member]
Components of net periodic benefit cost
Service cost
Interest cost	1,475	1,871	2,950	3,742
Expected return on plan assets	(2,225)	(2,342)	(4,450)	(4,684)
Amortization of Unrecognized actuarial (gain) loss	575	896	(850)	1,792
Amortization of Unrecognized prior service cost
Net periodic benefit cost (income)	(175)	425	(2,350)	850
Other Benefits [Member]
Components of net periodic benefit cost
Service cost	199	161	399	321
Interest cost	452	387	902	774
Expected return on plan assets	(8)	(9)	(16)	(18)
Amortization of Unrecognized actuarial (gain) loss	70	4	141	9
Amortization of Unrecognized prior service cost	(63)	(68)	(126)	(136)
Net periodic benefit cost (income)	$ 650	$ 475	$ 1,300	$ 950