Reclassifications from Accumulated Other Comprehensive Income - AOCI Roll Forward (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ (20,619)		$ (33,188)	$ (25,783)		$ (40,525)
Other comprehensive income (loss) before reclassifications	19,073		(6,978)	21,578		(9,980)
Amounts reclassified from accumulated other comprehensive income	(424)		4,179	2,235		14,518
Net current-period other comprehensive income	18,649		(2,799)	23,813		4,538
Balance at end of period	(1,970)		(35,987)	(1,970)		(35,987)
Net cumulative currency translation gains (losses)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(202)		252	(469)		(120)
Other comprehensive income (loss) before reclassifications	1		(753)	16		(381)
Amounts reclassified from accumulated other comprehensive income	0		0	252		0
Net current-period other comprehensive income	1		(753)	268		(381)
Balance at end of period	(201)		(501)	(201)		(501)
Net unrealized losses on qualifying cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(448)		(8,463)	(5,654)		(16,562)
Other comprehensive income (loss) before reclassifications	19,072		(6,183)	22,467		(8,308)
Amounts reclassified from accumulated other comprehensive income	(721)		3,837	1,090		14,061
Net current-period other comprehensive income	18,351		(2,346)	23,557		5,753
Balance at end of period	17,903		(10,809)	17,903		(10,809)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period			0			404
Other comprehensive income (loss) before reclassifications			0			157
Amounts reclassified from accumulated other comprehensive income			0			(561)
Net current-period other comprehensive income			0			(404)
Balance at end of period			0			0
Net unrecognized losses related to pension and severance plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(19,969)	[1]	(24,977)	(19,660)		(24,247)
Other comprehensive income (loss) before reclassifications	0		(42)	(905)		(1,448)
Amounts reclassified from accumulated other comprehensive income	297		342	893		1,018
Net current-period other comprehensive income	297		300	(12)		(430)
Balance at end of period	(19,672)	[1]	(24,677)	(19,672)	[1]	(24,677)
Deferred Tax Liabilities, Other Comprehensive Income	$ 0		$ 0	$ 0		$ 0	$ 271	$ 530	$ 0	$ 0

[1] Net of deferred tax liability of $271, $271, and $530 as of September 30, 2014, June 30, 2014, and December 31, 2013, respectively.