Accumulated Other Comprehensive Income (Loss) (AOCI balances) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, beginning balance	$ 453,480
Other comprehensive (loss) income before reclassifications	(17,385)
Net amount reclassified from accumulated other comprehensive income	457
Other Comprehensive (Loss) Income, Net of Tax	(16,928)	13,591
Accumulated Other Comprehensive Income, ending balance	436,552
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, beginning balance	8,548
Other comprehensive (loss) income before reclassifications	(12,088)
Net amount reclassified from accumulated other comprehensive income	(41)
Other Comprehensive (Loss) Income, Net of Tax	(12,129)
Accumulated Other Comprehensive Income, ending balance	(3,581)
Unrealized Gain on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, beginning balance	52,130
Other comprehensive (loss) income before reclassifications	(5,326)
Net amount reclassified from accumulated other comprehensive income	0
Other Comprehensive (Loss) Income, Net of Tax	(5,326)
Accumulated Other Comprehensive Income, ending balance	46,804
Unrealized Gain on Pensions and Other Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, beginning balance	392,910
Other comprehensive (loss) income before reclassifications	0
Net amount reclassified from accumulated other comprehensive income	419
Other Comprehensive (Loss) Income, Net of Tax	419
Accumulated Other Comprehensive Income, ending balance	393,329
Cash Flow Hedge [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income, beginning balance	(108)
Other comprehensive (loss) income before reclassifications	29
Net amount reclassified from accumulated other comprehensive income	79
Other Comprehensive (Loss) Income, Net of Tax	108
Accumulated Other Comprehensive Income, ending balance	$ 0