Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ (54,595)		$ (21,181)	$ (45,379)
Other comprehensive income before reclassifications	[1]	(31,825)		(33,075)	24,537
Amounts reclassified from accumulated other comprehensive loss	[1]	65,481		(339)	(339)
Other comprehensive income (loss)	[1]	33,656		(33,414)	24,198
Ending balance	[1]	(20,939)		(54,595)	(21,181)
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(364)		(637)	(902)
Other comprehensive income before reclassifications	[1]	253		273	265
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0	0
Other comprehensive income (loss)	[1]	253		273	265
Ending balance	[1]	(111)		(364)	(637)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(4,709)		0	0
Other comprehensive income before reclassifications	[1]	(7,332)		(4,709)	0
Amounts reclassified from accumulated other comprehensive loss		0	[1]		0
Other comprehensive income (loss)	[1]	(7,332)		(4,709)	0
Ending balance	[1]	(12,041)		(4,709)	0
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	126		7,861	2,569
Other comprehensive income before reclassifications	[1]	0		(7,735)	5,292
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0	0
Other comprehensive income (loss)	[1]	0		(7,735)	5,292
Ending balance	[1]	126		126	7,861
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(49,648)		(28,405)	(47,046)
Other comprehensive income before reclassifications	[1]	(24,746)		(20,904)	18,980
Amounts reclassified from accumulated other comprehensive loss	[1]	65,481		(339)	(339)
Other comprehensive income (loss)	[1]	40,735		(21,243)	18,641
Ending balance	[1]	$ (8,913)		$ (49,648)	$ (28,405)

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