Supplemental Consolidating Financial Information Condensed Statement of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net income (loss)	$ 17,836	$ 31,100	$ (6,767)	$ 33,477
Unrealized foreign currency translation gains	(1)	(17)	15	372
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	(252)	0
Net other comprehensive income (loss) related to foreign currency translation	(1)	(17)	267	372
Change in fair value of available-for-sale investment	0	0	0	157
Realized gains of available-for-sale investment reclassified into Other income (expense), net	0	0	0	(561)
Net other comprehensive income (loss) related to available-for-sale investment	0	0	0	(404)
Unrealized gains (losses) on derivatives for the period	4,441	(11,187)	3,395	(2,125)
Derivative (gains) losses reclassified into Net sales	1,020	6,582	2,047	15,214
Derivative gains reclassified into Cost of sales	(61)	(2,151)	(236)	(4,990)
Net other comprehensive income (loss) related to derivatives	5,400	(6,756)	5,206	8,099
Actuarial gains (losses) for the period, net of tax	(563)	15	(905)	(1,406)
Amortization included in pension cost	296	338	596	676
Net other comprehensive income (loss) related to defined benefit pension and severance plans	(267)	353	(309)	(730)
Other comprehensive income (loss)of investments in subsidiaries	0	0	0	0
Comprehensive income (loss)	22,968	24,680	(1,603)	40,814
Reportable Legal Entities [Member] | Parent Company [Member]
Net income (loss)	17,836	31,100	(6,767)	33,477
Unrealized foreign currency translation gains	0	0	0	0
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	0	0
Net other comprehensive income (loss) related to foreign currency translation	0	0	0	0
Change in fair value of available-for-sale investment				157
Realized gains of available-for-sale investment reclassified into Other income (expense), net				561
Net other comprehensive income (loss) related to available-for-sale investment				(404)
Unrealized gains (losses) on derivatives for the period	0	0	0	0
Derivative (gains) losses reclassified into Net sales	0	0	0	0
Derivative gains reclassified into Cost of sales	0	0	0	0
Net other comprehensive income (loss) related to derivatives	0	0	0	0
Actuarial gains (losses) for the period, net of tax	0	0	0	0
Amortization included in pension cost	0	0	0	0
Net other comprehensive income (loss) related to defined benefit pension and severance plans	0	0	0	0
Other comprehensive income (loss)of investments in subsidiaries	5,132	(6,420)	5,164	7,741
Comprehensive income (loss)	22,968	24,680	(1,603)	40,814
Reportable Legal Entities [Member] | Subsidiary Issuer [Member]
Net income (loss)	31,394	44,183	30,956	64,918
Unrealized foreign currency translation gains	0	0	0	0
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	0	0
Net other comprehensive income (loss) related to foreign currency translation	0	0	0	0
Change in fair value of available-for-sale investment				0
Realized gains of available-for-sale investment reclassified into Other income (expense), net				0
Net other comprehensive income (loss) related to available-for-sale investment				0
Unrealized gains (losses) on derivatives for the period	0	0	0	0
Derivative (gains) losses reclassified into Net sales	0	0	0	0
Derivative gains reclassified into Cost of sales	0	0	0	0
Net other comprehensive income (loss) related to derivatives	0	0	0	0
Actuarial gains (losses) for the period, net of tax	(564)	(15)	(565)	971
Amortization included in pension cost	102	124	206	248
Net other comprehensive income (loss) related to defined benefit pension and severance plans	462	(109)	359	(1,219)
Other comprehensive income (loss)of investments in subsidiaries	5,594	(6,529)	5,523	6,522
Comprehensive income (loss)	36,526	37,763	36,120	72,659
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Net income (loss)	5,798	2,367	2,686	7,358
Unrealized foreign currency translation gains	0	0	0	0
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	0	0
Net other comprehensive income (loss) related to foreign currency translation	0	0	0	0
Change in fair value of available-for-sale investment				0
Realized gains of available-for-sale investment reclassified into Other income (expense), net				0
Net other comprehensive income (loss) related to available-for-sale investment				0
Unrealized gains (losses) on derivatives for the period	0	0	0	0
Derivative (gains) losses reclassified into Net sales	0	0	0	0
Derivative gains reclassified into Cost of sales	0	0	0	0
Net other comprehensive income (loss) related to derivatives	0	0	0	0
Actuarial gains (losses) for the period, net of tax	0	0	0	0
Amortization included in pension cost	0	0	0	0
Net other comprehensive income (loss) related to defined benefit pension and severance plans	0	0	0	0
Other comprehensive income (loss)of investments in subsidiaries	0	0	0	0
Comprehensive income (loss)	5,798	2,367	2,686	7,358
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Net income (loss)	31,805	42,571	40,063	67,405
Unrealized foreign currency translation gains	(1)	(17)	15	372
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	(252)	0
Net other comprehensive income (loss) related to foreign currency translation	(1)	(17)	267	372
Change in fair value of available-for-sale investment				0
Realized gains of available-for-sale investment reclassified into Other income (expense), net				0
Net other comprehensive income (loss) related to available-for-sale investment				0
Unrealized gains (losses) on derivatives for the period	4,441	(11,187)	3,395	(2,125)
Derivative (gains) losses reclassified into Net sales	1,020	6,582	2,047	15,214
Derivative gains reclassified into Cost of sales	61	2,151	236	4,990
Net other comprehensive income (loss) related to derivatives	5,400	(6,756)	5,206	8,099
Actuarial gains (losses) for the period, net of tax	1	30	(340)	(2,377)
Amortization included in pension cost	194	214	390	428
Net other comprehensive income (loss) related to defined benefit pension and severance plans	(195)	(244)	(50)	1,949
Other comprehensive income (loss)of investments in subsidiaries	0	0	0	0
Comprehensive income (loss)	37,399	36,042	45,586	73,927
Consolidation, Eliminations [Member]
Net income (loss)	(68,997)	(89,121)	(73,705)	(139,681)
Unrealized foreign currency translation gains	0	0	0	0
Realized gains for foreign currency translation on business disposal reclassified into Other income (expense), net	0	0	0	0
Net other comprehensive income (loss) related to foreign currency translation	0	0	0	0
Change in fair value of available-for-sale investment				0
Realized gains of available-for-sale investment reclassified into Other income (expense), net				0
Net other comprehensive income (loss) related to available-for-sale investment				0
Unrealized gains (losses) on derivatives for the period	0	0	0	0
Derivative (gains) losses reclassified into Net sales	0	0	0	0
Derivative gains reclassified into Cost of sales	0	0	0	0
Net other comprehensive income (loss) related to derivatives	0	0	0	0
Actuarial gains (losses) for the period, net of tax	0	0	0	0
Amortization included in pension cost	0	0	0	0
Net other comprehensive income (loss) related to defined benefit pension and severance plans	0	0	0	0
Other comprehensive income (loss)of investments in subsidiaries	(10,726)	12,949	(10,687)	(14,263)
Comprehensive income (loss)	$ (79,723)	$ (76,172)	$ (84,392)	$ (153,944)