Pension Benefit and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 132			$ 2,342
Interest cost	2,004	1,869		6,012	5,884
Expected return on plan assets	(3,227)	(2,900)		(9,682)	(8,347)
Amortization of prior service cost					124
Amortization of net loss	172	545		515	3,070
Special termination benefit
Settlement charge				77
Curtailment charge			1,537		1,537
Net periodic benefit cost (income)	(1,051)	(354)		(3,078)	4,610
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	160	143		479	484
Interest cost	83	61		250	202
Expected return on plan assets
Amortization of prior service cost					(115)
Amortization of net loss	31			92	165
Special termination benefit		0
Settlement charge
Curtailment charge
Net periodic benefit cost (income)	$ 274	$ 204		$ 821	$ 736