Reclassifications from Accumulated Other Comprehensive Income - AOCI Roll Forward (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014		Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		$ (18,218)		$ (20,619)		$ (20,082)		$ (25,783)
Other comprehensive income (loss) before reclassifications		(621)		19,073		18,652		21,578
Amounts reclassified from accumulated other comprehensive income		(3,834)		(424)		(21,243)		2,235
Net current-period other comprehensive income		(4,455)		18,649		(2,591)		23,813
Balance at end of period		(22,673)		(1,970)		(22,673)		(1,970)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period				(202)		(290)		(469)
Other comprehensive income (loss) before reclassifications				1				16
Amounts reclassified from accumulated other comprehensive income				0				252
Net current-period other comprehensive income				1				268
Net unrealized losses on qualifying cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		271		(448)		7,299		(5,654)
Other comprehensive income (loss) before reclassifications		0		19,072		2		22,467
Amounts reclassified from accumulated other comprehensive income		0		(721)		559		1,090
Net current-period other comprehensive income		0		18,351		561		23,557
Balance at end of period		271		(201)		271		(201)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		4,736
Other comprehensive income (loss) before reclassifications		(620)				15,384
Amounts reclassified from accumulated other comprehensive income		(4,116)				(22,683)
Net current-period other comprehensive income		(4,736)				(7,299)
Balance at end of period		0		17,903		0		17,903
Net unrecognized losses related to pension and severance plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period		(23,225)	[1]	(19,969)	[2]	(27,091)	[1]	(19,660)	[2]
Other comprehensive income (loss) before reclassifications		(1)		0		3,266		(905)
Amounts reclassified from accumulated other comprehensive income		282		297		881		893
Net current-period other comprehensive income		281		297		4,147		(12)
Balance at end of period	[1]	$ (22,944)		(19,672)		$ (22,944)		(19,672)
Deferred Tax Liabilities, Other Comprehensive Income				$ 0				$ 0		$ 1	$ 0	$ 0	$ 1

[1] (1) Net of deferred tax asset of $521 thousand, $521 thousand and $401 thousand as of September 30, 2015, June 30, 2015 and December 31, 2014, respectively.

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