Pension and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 1,498	$ 1,291
Interest cost	3,129	3,144
Expected return on plan assets	(4,031)	(3,929)
Amortization of prior service cost (credit)	64	68
Amortization of net actuarial loss	2,313	2,063
Settlement loss		1,716
Net periodic benefit cost for continuing operations	2,973	4,353
Other Benefits
Components of net periodic benefit cost:
Service cost	2,018	1,253
Interest cost	7,253	6,202
Amortization of prior service cost (credit)	261	(240)
Amortization of net actuarial loss	3,681	3,052
Net periodic benefit cost for continuing operations	$ 13,213	$ 10,267