Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Benefit Plans (Textuals)
Contributions to qualified and non qualified pension plans	$ 761		$ 12,864
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	30,000
Components of net periodic benefit cost
Service cost	3,331		2,862
Interest cost	6,957		7,958
Expected return on plan assets	(8,803)		(10,205)
Amortization of prior service cost (benefit)	18		65
Recognized net actuarial loss	5,421		4,211
Curtailment loss (1)	1,159	[1]	0	[1]
Net periodic pension benefit cost	8,083		4,891
Other Benefits [Member]
Components of net periodic benefit cost
Service cost	0		0
Interest cost	157		204
Expected return on plan assets	0		0
Amortization of prior service cost (benefit)	(122)		(129)
Recognized net actuarial loss	106		121
Curtailment loss (1)	0	[1]	0	[1]
Net periodic pension benefit cost	$ 141		$ 196

[1] The curtailment loss during the first quarter of 2013 resulted from the departure of certain executive officers and was recorded within selling and administrative expense.