Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	$ (21,181)	[1]	$ (45,379)	[1]
Other comprehensive income before reclassifications	(33,075)	[1]	24,537	[1]
Amounts reclassified from accumulated other comprehensive loss	(339)	[1]	(339)	[1]
Other comprehensive income (loss)	(33,414)	[1]	24,198	[1]	(2,289)
Ending balance	(54,595)	[1]	(21,181)	[1]	(45,379)	[1]
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(637)	[1]	(902)	[1]
Other comprehensive income before reclassifications	273	[1]	265	[1]
Amounts reclassified from accumulated other comprehensive loss	0	[1]	0	[1]
Other comprehensive income (loss)	273	[1]	265	[1]
Ending balance	(364)	[1]	(637)	[1]
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	0	[1]
Other comprehensive income before reclassifications	(4,709)	[1]
Amounts reclassified from accumulated other comprehensive loss	0	[1]
Other comprehensive income (loss)	(4,709)	[1]
Ending balance	(4,709)	[1]
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	7,861	[1]	2,569	[1]
Other comprehensive income before reclassifications	(7,735)	[1]	5,292	[1]
Amounts reclassified from accumulated other comprehensive loss	0	[1]	0	[1]
Other comprehensive income (loss)	(7,735)	[1]	5,292	[1]
Ending balance	126	[1]	7,861	[1]
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	(28,405)	[1]	(47,046)	[1]
Other comprehensive income before reclassifications	(20,904)	[1]	18,980	[1]
Amounts reclassified from accumulated other comprehensive loss	(339)	[1]	(339)	[1]
Other comprehensive income (loss)	(21,243)	[1]	18,641	[1]
Ending balance	$ (49,648)	[1]	$ (28,405)	[1]

[1] All amounts are net of tax. Amounts in parentheses indicate debits