Pension Benefit and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended		9 Months Ended		3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2013 Pension Benefits [Member]	Jun. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Jun. 30, 2013 Pension Benefits [Member]		Sep. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Sep. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Jun. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2012 Retirement Health and Life Insurance Benefits [Member]	Mar. 31, 2012 Retirement Health and Life Insurance Benefits [Member]	Jun. 30, 2012 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2013 Retirement Health and Life Insurance Benefits [Member]	Sep. 30, 2012 Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 132		$ 1,150	$ 2,210	[1]	$ 2,342	$ 3,447	$ 143		$ 149			$ 484	$ 481
Interest cost	1,869		2,094	4,015	[1]	5,884	6,336	61		92			202	272
Expected return on plan assets	(2,900)		(2,495)			(8,347)	(7,397)
Amortization of prior service cost			116			124	347			(113)			(115)	(338)
Amortization of net loss	545		1,347			3,070	4,138			66			165	247
Special termination benefit				0	[1]				(700)	0	2,300	1,593		1,593
Settlement charge			2,023				2,023
Curtailment charge		1,537				1,537
Net periodic benefit cost (income)	$ (354)		$ 4,235			$ 4,610	$ 8,894	$ 204		$ 194			$ 736	$ 2,255

[1] This calculation was performed as of June 30, 2013 due to the pension freeze and we are not otherwise required to perform the calculation at interim periods