Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	$ (20,939)		$ (54,595)	$ (21,181)
Other comprehensive income before reclassifications	[1]	8,818		(31,825)	(33,075)
Amounts reclassified from accumulated other comprehensive loss	[1]	(347)		65,481	(339)
Other comprehensive income (loss)	[1]	8,471		33,656	(33,414)
Ending balance	[1]	(12,468)		(20,939)	(54,595)
Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(111)		(364)	(637)
Other comprehensive income before reclassifications	[1]	111		253	273
Amounts reclassified from accumulated other comprehensive loss	[1]	0		0	0
Other comprehensive income (loss)	[1]	111		253	273
Ending balance	[1]	0		(111)	(364)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(12,041)		(4,709)	0
Other comprehensive income before reclassifications	[1]	1,039		(7,332)	(4,709)
Amounts reclassified from accumulated other comprehensive loss		0	[1]		0
Other comprehensive income (loss)	[1]	1,039		(7,332)	(4,709)
Ending balance	[1]	(11,002)		(12,041)	(4,709)
Investment in Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	126		126	7,861
Other comprehensive income before reclassifications	[1]	0		0	(7,735)
Amounts reclassified from accumulated other comprehensive loss	[1]	(126)		0	0
Other comprehensive income (loss)	[1]	(126)		0	(7,735)
Ending balance	[1]	0		126	126
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance	[1]	(8,913)		(49,648)	(28,405)
Other comprehensive income before reclassifications	[1]	7,668		(24,746)	(20,904)
Amounts reclassified from accumulated other comprehensive loss	[1]	(221)		65,481	(339)
Other comprehensive income (loss)	[1]	7,447		40,735	(21,243)
Ending balance	[1]	$ (1,466)		$ (8,913)	$ (49,648)

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