Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 165,658		$ 162,111	$ 159,468		$ 172,172
Restricted cash	136		6,830
Accounts receivable, net	148,537		125,922
Inventories, net	75,020		62,836
Other receivables	2,097		256
Prepaid expenses	9,120		6,032
Other current assets	19,270		15,909
Total current assets	419,838		379,896
Property, plant and equipment, net	229,632		182,663
Intangible assets, net	16,684		16,787
Long-term prepaid expenses	9,575		4,790
Other non-current assets	17,044		18,539
Total assets	692,773		602,675
Current liabilities
Accounts payable	97,386		77,848
Other accounts payable	19,049		13,452
Accrued expenses	40,483		31,723
Derivative liabilities	1,818		9,757
Current portion of capital lease obligations			2,852
Other current liabilities	8,460		11,764
Total current liabilities	167,196		137,639
Long-term borrowings, net	201,586		201,389
Accrued severance benefits, net	105,051		90,755
Other non-current liabilities	11,556		6,222
Total liabilities	485,389		436,005
Commitments and contingencies
Stockholders' equity
Common stock	395		394
Additional paid-in capital	100,834		98,929
Retained earnings	161,965		93,950
Treasury stock	(34,730)		(11,793)
Accumulated other comprehensive loss	(21,080)		(14,810)
Total stockholders' equity	207,384	170,548	166,670	159,947	189,814	162,851
Total liabilities and stockholders' equity	692,773		602,675
MagnaChip Semiconductor Corporation (Parent) [Member]
Current assets
Cash and cash equivalents	827		1,677	1,408		79
Other receivables	399		1
Prepaid expenses	102		34
Other current assets	78,395		58,636
Total current assets	79,723		60,348
Investment in subsidiaries	(526,931)		(576,642)
Long-term intercompany loan	697,125		697,125
Other non-current assets	67
Total assets	249,984		180,831
Current liabilities
Other accounts payable	38,386		13,659
Accrued expenses	174		502
Other current liabilities	4,040
Total current liabilities	42,600		14,161
Total liabilities	42,600		14,161
Commitments and contingencies
Stockholders' equity
Common stock	395		394
Additional paid-in capital	100,834		98,929
Retained earnings	161,965		93,950
Treasury stock	(34,730)		(11,793)
Accumulated other comprehensive loss	(21,080)		(14,810)
Total stockholders' equity	207,384		166,670
Total liabilities and stockholders' equity	249,984		180,831
Co-Issuers [Member]
Current assets
Cash and cash equivalents	12,253		25,119	25,688		46,595
Other receivables	36,276		11,793
Prepaid expenses			2
Other current assets	226,332		188,018
Total current assets	274,861		224,932
Investment in subsidiaries	(608,299)		(655,845)
Long-term intercompany loan	787,364		809,913
Other non-current assets	5,949		6,505
Total assets	459,875		385,505
Current liabilities
Other accounts payable	36		1
Accrued expenses	87,682		63,033
Other current liabilities			1
Total current liabilities	87,718		63,035
Long-term borrowings, net	898,711		898,514
Total liabilities	986,429		961,549
Commitments and contingencies
Stockholders' equity
Common stock	136,229		136,229
Additional paid-in capital	(731,689)		(733,223)
Retained earnings	89,985		35,760
Accumulated other comprehensive loss	(21,079)		(14,810)
Total stockholders' equity	(526,554)		(576,044)
Total liabilities and stockholders' equity	459,875		385,505
Non-Guarantors [Member]
Current assets
Cash and cash equivalents	145,921		127,118	121,344		112,370
Restricted cash	136		6,830
Accounts receivable, net	149,507		126,391
Inventories, net	75,020		62,836
Other receivables	7,790		7,581
Prepaid expenses	11,580		8,509
Other current assets	15,430		11,738
Total current assets	405,384		351,003
Property, plant and equipment, net	229,539		182,583
Intangible assets, net	16,524		16,514
Long-term prepaid expenses	13,639		10,963
Other non-current assets	8,429		8,170
Total assets	673,515		569,233
Current liabilities
Accounts payable	119,220		99,560
Other accounts payable	19,349		13,115
Accrued expenses	219,323		186,678
Derivative liabilities	1,818
Current portion of capital lease obligations			2,852
Other current liabilities	3,243		11,544
Total current liabilities	362,953		313,749
Long-term borrowings, net	621,000		642,383
Accrued severance benefits, net	104,867		90,611
Other non-current liabilities	9,261		3,894
Total liabilities	1,098,081		1,050,637
Commitments and contingencies
Stockholders' equity
Common stock	39,005		39,005
Additional paid-in capital	(535,358)		(536,894)
Retained earnings	96,017		35,141
Accumulated other comprehensive loss	(24,230)		(18,656)
Total stockholders' equity	(424,566)		(481,404)
Total liabilities and stockholders' equity	673,515		569,233
Guarantors [Member]
Current assets
Cash and cash equivalents	6,657		8,197	11,028		13,128
Accounts receivable, net	22,328		22,179
Inventories, net			158
Other receivables	364		399
Prepaid expenses	335		384
Other current assets	192,979		183,685
Total current assets	222,663		215,002
Property, plant and equipment, net	93		80
Intangible assets, net	160		273
Long-term prepaid expenses			66
Investment in subsidiaries	(424,624)		(481,478)
Long-term intercompany loan	638,690		660,066
Other non-current assets	2,665		3,864
Total assets	439,647		397,873
Current liabilities
Accounts payable	1,143		842
Other accounts payable	4,331		6,195
Accrued expenses	227,170		207,770
Other current liabilities	4,072		3,117
Total current liabilities	236,716		217,924
Long-term borrowings, net	805,054		827,596
Accrued severance benefits, net	184		144
Other non-current liabilities	6,426		8,567
Total liabilities	1,048,380		1,054,231
Commitments and contingencies
Stockholders' equity
Common stock	51,976		51,976
Additional paid-in capital	(729,663)		(731,209)
Retained earnings	90,215		37,722
Accumulated other comprehensive loss	(21,261)		(14,847)
Total stockholders' equity	(608,733)		(656,358)
Total liabilities and stockholders' equity	439,647		397,873
Eliminations [Member]
Current assets
Accounts receivable, net	(23,298)		(22,648)
Inventories, net			(158)
Other receivables	(42,732)		(19,518)
Prepaid expenses	(2,897)		(2,897)
Other current assets	(493,866)		(426,168)
Total current assets	(562,793)		(471,389)
Long-term prepaid expenses	(4,064)		(6,239)
Investment in subsidiaries	1,559,854		1,713,965
Long-term intercompany loan	(2,123,179)		(2,167,104)
Other non-current assets	(66)
Total assets	(1,130,248)		(930,767)
Current liabilities
Accounts payable	(22,977)		(22,554)
Other accounts payable	(43,053)		(19,518)
Accrued expenses	(493,866)		(426,260)
Other current liabilities	(2,895)		(2,898)
Total current liabilities	(562,791)		(471,230)
Long-term borrowings, net	(2,123,179)		(2,167,104)
Other non-current liabilities	(4,131)		(6,239)
Total liabilities	(2,690,101)		(2,644,573)
Commitments and contingencies
Stockholders' equity
Common stock	(227,210)		(227,210)
Additional paid-in capital	1,996,710		2,001,326
Retained earnings	(276,217)		(108,623)
Accumulated other comprehensive loss	66,570		48,313
Total stockholders' equity	1,559,853		1,713,806
Total liabilities and stockholders' equity	$ (1,130,248)		$ (930,767)