Accumulated Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income or Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance					$ (57,808)		$ (62,802)
Other comprehensive income before reclassifications					4,896		446
Actuarial net gain (loss) incurred in the fiscal year	0		0		17,225		0
Amounts reclassified from accumulated other comprehensive income					3,107		5,339
Net current-period other comprehensive income					25,228		5,785
Ending balance	(32,580)		(57,017)		(32,580)		(57,017)
AOCI, Pension and other postretirement benefit plans, tax	11,423		18,553		11,423		18,553		22,371	20,799
AOCI, Cumulative changes in net gain (loss) from cash flow hedges, tax	116		0		116		0		127	0
AOCI, Available-for-sale securities adjustment, tax										1,555
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance					12,585		5,875
Other comprehensive income before reclassifications					4,877		530
Actuarial net gain (loss) incurred in the fiscal year					0
Amounts reclassified from accumulated other comprehensive income					0		0
Net current-period other comprehensive income					4,877		530
Ending balance	17,462		6,405		17,462		6,405
Funded status of pension plans and other postretirement benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance					(70,158)	[1]	(67,239)	[2]
Other comprehensive income before reclassifications					0	[1]	0	[2]
Actuarial net gain (loss) incurred in the fiscal year					17,225	[1]
Amounts reclassified from accumulated other comprehensive income					3,107	[1]	4,171	[2]
Net current-period other comprehensive income					20,332	[1]	4,171	[2]
Ending balance	(49,826)	[1]	(63,068)	[2]	(49,826)	[1]	(63,068)	[2]
Unrealized gain (loss) on derivative instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance					(235)	[3]	(270)	[4]
Other comprehensive income before reclassifications					19	[3]	(84)	[4]
Actuarial net gain (loss) incurred in the fiscal year					0	[3]
Amounts reclassified from accumulated other comprehensive income					0	[3]	0	[4]
Net current-period other comprehensive income					19	[3]	(84)	[4]
Ending balance	(216)	[3]	(354)	[4]	(216)	[3]	(354)	[4]
Unrealized gain (loss) on marketable securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance							(1,168)	[5]
Other comprehensive income before reclassifications							0	[5]
Amounts reclassified from accumulated other comprehensive income							1,168	[5]
Net current-period other comprehensive income							1,168	[5]
Ending balance			$ 0	[5]			$ 0	[5]

[1] Net of taxes of $11,423 and $22,371 for the periods ended September 30, 2013 and December 31, 2012, respectively.

[2] Net of taxes of 18,553 and $20,799 for the periods ended September 30, 2012 and December 31, 2011, respectively.

[3] Net of taxes of $116 and $127 for the periods ended September 30, 2013 and December 31, 2012, respectively.

[4] Net of taxes of $0 and $0 for the periods ended September 30, 2012 and December 31, 2011, respectively.

[5] Net of taxes of $1,555 for the period ended December 31, 2011.