Amkor Technology (AMKR) 10-Q 30 Apr 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	3 Months Ended
	Mar. 31, 2015	Apr. 24, 2015
Document Information [Line Items]
Entity Registrant Name	AMKOR TECHNOLOGY, INC.
Entity Central Index Key	1047127
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		237,374,103

Consolidated_Statements_of_Inc

Consolidated Statements of Income (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net sales	$742,875	$696,044
Cost of sales	607,928	567,224
Gross profit	134,947	128,820
Selling, general and administrative	62,942	62,424
Research and development	18,026	21,045
Total operating expenses	80,968	83,469
Operating income	53,979	45,351
Interest expense	23,777	23,722
Interest expense, related party	1,242	1,242
Other (income) expense, net	-498	36
Total other expense, net	24,521	25,000
Income before taxes and equity in earnings of unconsolidated affiliate	29,458	20,351
Income tax expense	5,999	4,929
Income before equity in earnings of unconsolidated affiliate	23,459	15,422
Equity in earnings of J-Devices	6,238	5,761
Net income	29,697	21,183
Net income attributable to noncontrolling interests	-916	-550
Net income attributable to Amkor	$28,781	$20,633
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$0.12	$0.09
Diluted (in dollars per share)	$0.12	$0.09
Shares used in computing per common share amounts:
Basic (in shares)	236,708	216,757
Diluted (in shares)	237,424	235,497

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net income	$29,697	$21,183
Other comprehensive income, net of tax:
Adjustments to unrealized components of defined benefit pension plans, net of tax	22	120
Foreign currency translation adjustment	-122	685
Equity interest in J-Devices' other comprehensive income, net of tax	1,338	3,144
Total other comprehensive income	1,238	3,949
Comprehensive income	30,935	25,132
Comprehensive income attributable to noncontrolling interests	-916	-550
Comprehensive income attributable to Amkor	$30,019	$24,582

Consolidated_Balance_Sheets_Un

Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$494,189	$449,946
Restricted cash	2,681	2,681
Accounts receivable, net of allowances	433,092	469,683
Inventories	227,605	223,379
Other current assets	48,383	52,259
Total current assets	1,205,950	1,197,948
Property, plant and equipment, net	2,167,790	2,206,476
Investments	138,218	117,733
Restricted cash	2,151	2,123
Other assets	119,767	111,125
Total assets	3,633,876	3,635,405
Current liabilities:
Short-term borrowings and current portion of long-term debt	30,000	5,000
Trade accounts payable	287,129	309,025
Capital expenditures payable	111,646	127,568
Accrued expenses	272,620	258,997
Total current liabilities	701,395	700,590
Long-term debt	1,420,677	1,450,824
Long-term debt, related party	75,000	75,000
Pension and severance obligations	153,027	152,673
Other non-current liabilities	120,193	125,382
Total liabilities	2,470,292	2,504,469
Commitments and contingencies (Note 17)
Amkor stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized, designated Series A, none issued	0	0
Common stock, $0.001 par value, 500,000 shares authorized, 282,439 and 282,231 shares issued, and 236,804 and 236,627 shares outstanding, in 2015 and 2014, respectively	282	282
Additional paid-in capital	1,880,753	1,878,810
Accumulated deficit	-488,181	-516,962
Accumulated other comprehensive loss	-31,629	-32,867
Treasury stock, at cost, 45,635 and 45,604 shares in 2015 and 2014, respectively	-213,258	-213,028
Total Amkor stockholders’ equity	1,147,967	1,116,235
Noncontrolling interests in subsidiaries	15,617	14,701
Total equity	1,163,584	1,130,936
Total liabilities and equity	$3,633,876	$3,635,405

Consolidated_Balance_Sheets_Un1

Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, except Per Share data, unless otherwise specified
Amkor stockholders’ equity:
Preferred stock designated Series A, par value (in dollars per share)	$0.00	$0.00
Preferred stock designated Series A, shares authorized	10,000	10,000
Preferred stock designated Series A, shares issued	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	500,000	500,000
Common stock, shares issued	282,439	282,231
Common stock, shares outstanding	236,804	236,627
Treasury stock, shares	45,635	45,604

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$29,697	$21,183
Depreciation and amortization	124,387	108,338
Other operating activities and non-cash items	-9,525	-4,274
Changes in assets and liabilities	20,465	6,699
Net cash provided by operating activities	165,024	131,946
Cash flows from investing activities:
Payments for property, plant and equipment	-106,149	-95,999
Proceeds from sale of property, plant and equipment	3,254	726
Investment in J-Devices	-12,908	0
Other investing activities	-322	-266
Net cash used in investing activities	-116,125	-95,539
Cash flows from financing activities:
Borrowings under revolving credit facilities	30,000	0
Proceeds from issuance of long-term debt	0	80,000
Payments of long-term debt	-35,000	-80,000
Payment of deferred consideration for an acquisition	0	-18,763
Proceeds from the issuance of stock through share-based compensation plans	574	438
Payments of tax withholding for restricted shares	-230	-122
Net cash used in financing activities	-4,656	-18,447
Effect of exchange rate fluctuations on cash and cash equivalents	0	183
Net increase in cash and cash equivalents	44,243	18,143
Cash and cash equivalents, beginning of period	449,946	610,442
Cash and cash equivalents, end of period	494,189	628,585
Non cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	$111,646	$144,302

Interim_Financial_Statements

Interim Financial Statements	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interim Financial Statements	1.    Interim Financial Statements
	Basis of Presentation. The Consolidated Financial Statements and related disclosures as of March 31, 2015, and for the three months ended March 31, 2015 and 2014, are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2014, Consolidated Balance Sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. In our opinion, these financial statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods. These financial statements should be read in conjunction with the financial statements included in our Annual Report for the year ended December 31, 2014, filed on Form 10-K with the SEC on February 19, 2015. The results of operations for the three months ended March 31, 2015, are not necessarily indicative of the results to be expected for the full year. Unless the context otherwise requires, all references to “Amkor,” “we,” “us,” “our” or the “company” are to Amkor Technology, Inc. and our subsidiaries.
	On June 30, 2014, we completed the sale of our Japanese subsidiary to J-Devices, our equity-method joint venture in Japan. The financial results of the entity were included in our consolidated financial statements up to the date of sale (Note 3) and have subsequently been included in the results of J-Devices.
	The U.S. dollar is our reporting currency and the functional currency for our subsidiaries. Effective June 30, 2014, we changed the functional currency for our sales office in Japan to the U.S. dollar primarily due to an increase in the mix of our U.S. dollar denominated sales. The change in functional currency is applied on a prospective basis.
	Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments.

New_Accounting_Standards

New Accounting Standards	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	2.    New Accounting Standards
	Recently Issued Standards
	In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 is based on the principle that revenue is recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and changes in judgments. ASU 2014-09 is effective for reporting periods beginning after December 15, 2016; however, the FASB is contemplating changes to the new standard and its effective date. ASU 2014-09 permits the use of either full retrospective or modified retrospective methods of adoption. Early adoption is not permitted. We are currently evaluating the method of adoption and the impact that this guidance will have on our financial statements and disclosure.
	In April 2015, the FASB issued ASU 2015-03, Interest-Imputation of Interest (Subtopic 835-30) - Simplifying the Presentation of Debt Issuance Costs. ASU 2015-03 requires debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for reporting periods beginning after December 15, 2015, and requires retrospective application. Early adoption is permitted. ASU 2015-03 is not expected to have a significant impact on our financial statements and disclosure.
	In April 2015, the FASB issued ASU 2015-05, Intangibles - Goodwill and Other Internal-Use Software (Subtopic 350-40) - Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The new guidance does not change the accounting for a customer's accounting for service contracts. ASU No. 2015-05 is effective for interim and annual reporting periods beginning after December 15, 2015. Early adoption is permitted. We are currently evaluating the impact that this guidance will have on our financial statements and disclosure.

Sale_of_Subsidiary_to_JDevices

Sale of Subsidiary to J-Devices	3 Months Ended
	Mar. 31, 2015
Disposal Group, Not Discontinued Operation, Disposal Disclosures [Abstract]
Sale of Subsidiary to J-Devices	3.    Sale of Subsidiary to J-Devices
	On June 30, 2014, we sold 100% of the shares of our wholly-owned subsidiary engaged in semiconductor packaging and test operations in Japan to J-Devices Corporation ("J-Devices"), our equity-method joint venture in Japan, for ¥1.1 billion ($9.5 million). For additional information regarding our investment in J-Devices, we refer you to Note 12. We received ¥0.1 billion ($1.0 million) in cash from J-Devices at closing and will receive the remaining ¥1.0 billion ($8.5 million) by June 30, 2015. We recognized a net gain on the sale of $9.2 million in our consolidated financial statements in other (income) expense, net, which includes a gain of $12.6 million from the release of accumulated foreign currency translation adjustments associated with the entity. J-Devices recognized a gain of $14.7 million on the transaction in its consolidated financial statements as the fair value of the net assets acquired exceeded the purchase price. The gain recognized by J-Devices increased our equity in earnings of J-Devices by $8.8 million. The combined net gain we recognized was $18.0 million.

ShareBased_Compensation_Plans

Share-Based Compensation Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation Plans	4.    Share-Based Compensation Plans
	For the three months ended March 31, 2015 and 2014, we recognized share-based compensation attributable to stock options and restricted shares of $1.4 million and $1.0 million, respectively, primarily in selling, general and administrative expenses. There were no corresponding deferred income tax benefits for stock options or restricted shares.
	Stock Options
	The following table summarizes our stock option activity for the three months ended March 31, 2015:
		Number of			Weighted Average				Weighted Average	Aggregate
		Shares			Exercise Price				Remaining	Intrinsic
		(In thousands)			Per Share				Contractual	Value
									Term (Years)	(In thousands)
	Outstanding at December 31, 2014	3,822			$	6.25
	Granted	100			8.92
	Exercised	(119	)		4.81
	Forfeited or expired	(69	)		4.28
	Outstanding at March 31, 2015	3,734			$	6.41			6.22	$	10,424
	Fully vested at March 31, 2015 and expected to vest thereafter	3,706			$	6.41			6.21	$	10,329
	Exercisable at March 31, 2015	2,244			$	7			4.83	$	5,330
	The following assumptions were used to calculate the weighted average fair values of the options granted:
		For the Three Months Ended
		March 31,
		2015				2014
	Expected life (in years)	6.1				6.1
	Risk-free interest rate	1.7		%		1.9		%
	Volatility	50		%		59		%
	Dividend yield	—				—
	Weighted average grant date fair value per option granted	$	4.38			$	2.89
	Total unrecognized compensation expense from stock options, net of a forfeiture estimate, was $3.6 million as of March 31, 2015, which is expected to be recognized over a weighted-average period of approximately 2.3 years beginning April 1, 2015.
	Restricted Shares
	The following table summarizes our restricted share activity for the three months ended March 31, 2015:
		Number of			Weighted
		Shares			Average
		(In thousands)			Grant-Date
					Fair Value
					(Per share)
	Nonvested at December 31, 2014	660			$	4.58
	Awards granted	8			9.85
	Awards vested	(89	)		5.27
	Awards forfeited	(17	)		4.46
	Nonvested at March 31, 2015	562			$	4.55
	Total unrecognized compensation cost from restricted shares, net of a forfeiture estimate, was $2.2 million as of March 31, 2015, which is expected to be recognized over a weighted average period of approximately 2.0 years beginning April 1, 2015.

Other_Income_and_Expense

Other Income and Expense	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
Other Income and Other Expense Disclosure [Text Block]	5.    Other Income and Expense
	Other income and expense consists of the following:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Interest income	$	(983	)	$	(711	)
	Foreign currency loss, net	207			334
	Other expense, net	278			413
	Total other (income) expense, net	$	(498	)	$	36

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	6.    Income Taxes
	Our income tax expense of $6.0 million for the three months ended March 31, 2015 primarily reflects income taxes at certain of our foreign operations and foreign withholding taxes. Our income tax expense also reflects income taxed in foreign jurisdictions where we benefit from tax holidays.
	We maintain a valuation allowance on all of our U.S. net deferred tax assets, including our net operating loss carryforwards. We also have valuation allowances on deferred tax assets in certain foreign jurisdictions. Such valuation allowances are released as the related tax benefits are realized or when sufficient net positive evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized.
	Unrecognized tax benefits represent reserves for potential tax deficiencies or reductions in tax benefits that could result from federal, state or foreign tax audits. Our gross unrecognized tax benefits were $12.7 million at March 31, 2015 and December 31, 2014. At March 31, 2015, all of our unrecognized tax benefits would reduce our effective tax rate, if recognized. Our unrecognized tax benefits are subject to change as examinations of tax years are completed. Tax return examinations involve uncertainties, and there can be no assurances that the outcome of examinations will be favorable.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	7.    Earnings Per Share
	Basic earnings per share (“EPS”) is computed by dividing net income attributable to Amkor common stockholders by the weighted average number of common shares outstanding during the period. The weighted average number of common shares outstanding includes restricted shares held by retirement eligible recipients and is reduced for treasury stock. We grant restricted shares which entitle recipients to voting and nonforfeitable dividend rights from the date of grant therefore our unvested share-based compensation awards are considered participating securities and are included in the computation of EPS pursuant to the two-class method.
	Diluted EPS is computed on the basis of the weighted average number of shares of common stock plus the effect of dilutive potential common shares outstanding during the period. Dilutive potential common shares include outstanding stock options, unvested restricted shares and convertible debt. The following table summarizes the computation of basic and diluted EPS:
		For the Three Months Ended
		March 31,
		2015				2014
		(In thousands,
		except per share data)
	Net income attributable to Amkor	$	28,781			$	20,633
	Income allocated to participating securities	(68		)		(105		)
	Net income available to Amkor common stockholders — basic	28,713				20,528
	Adjustment for dilutive securities on net income:
	Net income reallocated to participating securities	—				3
	Interest on 6.0% convertible notes due 2014, net of tax	—				907
	Net income attributable to Amkor — diluted	$	28,713			$	21,438
	Weighted average shares outstanding — basic	236,708				216,757
	Effect of dilutive securities:
	Stock options	716				109
	6.0% convertible notes due 2014	—				18,631
	Weighted average shares outstanding — diluted	237,424				235,497
	Net income attributable to Amkor per common share:
	Basic	$	0.12			$	0.09
	Diluted	0.12				0.09
	The following table summarizes the potential shares of common stock that were excluded from diluted EPS, because the effect of including these potential shares was antidilutive:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Stock options and restricted share awards	1,400			4,265

Equity_and_Accumulated_Other_C

Equity and Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Equity and Accumulated Other Comprehensive Income	8.    Equity and Accumulated Other Comprehensive Income (Loss)
	The following tables reflect the changes in equity attributable to both Amkor and the noncontrolling interests:
		Attributable			Attributable to			Total
		to Amkor			Noncontrolling
					Interests
		(In thousands)
	Equity at December 31, 2014	$	1,116,235		$	14,701		$	1,130,936
	Net income	28,781			916			29,697
	Other comprehensive income	1,238			—			1,238
	Issuance of stock through employee share-based compensation plans	574			—			574
	Treasury stock acquired through surrender of shares for tax withholding	(230		)	—			(230		)
	Share-based compensation expense	1,369			—			1,369
	Equity at March 31, 2015	$	1,147,967		$	15,617		$	1,163,584
		Attributable			Attributable to			Total
		to Amkor			Noncontrolling
					Interests
		(In thousands)
	Equity at December 31, 2013	$	953,740		$	11,200		$	964,940
	Net income	20,633			550			21,183
	Other comprehensive income	3,949			—			3,949
	Issuance of stock through employee share-based compensation plans	438			—			438
	Treasury stock acquired through surrender of shares for tax withholding	(122		)	—			(122		)
	Share-based compensation expense	972			—			972
	Equity at March 31, 2014	$	979,610		$	11,750		$	991,360
	The following tables reflect the changes in accumulated other comprehensive income (loss), net of tax:
		Defined Benefit Pension			Foreign Currency Translation			Equity Interest in J-Devices' Other Comprehensive Income (Loss)			Total
		(In thousands)
	Accumulated other comprehensive loss at	$	(2,525	)	$	(513	)	$	(29,829	)	$	(32,867	)
	31-Dec-14
	Other comprehensive (loss) income before reclassifications	—			(122		)	1,338			1,216
	Amounts reclassified from accumulated other comprehensive loss	22			—			—			22
	Other comprehensive income (loss)	22			(122		)	1,338			1,238
	Accumulated other comprehensive loss at	$	(2,503	)	$	(635	)	$	(28,491	)	$	(31,629	)
	31-Mar-15
		Defined Benefit Pension			Foreign Currency Translation			Equity Interest in J-Devices' Other Comprehensive Income (Loss)			Total
		(In thousands)
	Accumulated other comprehensive (loss) income at	$	(1,013	)	$	11,451		$	(10,693	)	$	(255	)
	31-Dec-13
	Other comprehensive income before reclassifications	—			685			3,144			3,829
	Amounts reclassified from accumulated other comprehensive (loss) income	120			—			—			120
	Other comprehensive income	120			685			3,144			3,949
	Accumulated other comprehensive (loss) income at	$	(893	)	$	12,136		$	(7,549	)	$	3,694
	31-Mar-14
	Amounts reclassified out of accumulated other comprehensive (loss) income are included as a component of net periodic pension cost (Note 15).

Factoring_of_Accounts_Receivab

Factoring of Accounts Receivable	3 Months Ended
	Mar. 31, 2015
Factoring of Accounts Receivable [Abstract]
Factoring of Accounts Receivable [Table Text Block]	9.    Factoring of Accounts Receivable
	In certain foreign locations, we use non-recourse factoring arrangements with third party financial institutions to manage our working capital and cash flows. Under this program, we sell receivables to a financial institution for cash at a discount to the face amount. As part of the factoring arrangements, we perform certain collection and administrative functions for the receivables sold. For the three months ended March 31, 2015 and 2014, we sold accounts receivable totaling $81.3 million and $69.0 million, respectively, for a discount, plus fees, of $0.4 million and $0.3 million, respectively.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventories	10.    Inventories
	Inventories consist of the following:
		March 31,		December 31, 2014
		2015
		(In thousands)
	Raw materials and purchased components	$	162,250	$	161,942
	Work-in-process	65,355		61,437
	Total inventories	$	227,605	$	223,379

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant And Equipment	11.    Property, Plant and Equipment
	Property, plant and equipment consist of the following:
		March 31,			December 31, 2014
		2015
		(In thousands)
	Land	$	207,985		$	207,985
	Land use rights	26,845			26,845
	Buildings and improvements	944,246			940,846
	Machinery and equipment	3,977,069			3,953,891
	Software and computer equipment	186,868			185,243
	Furniture, fixtures and other equipment	16,274			15,347
	Construction in progress	64,324			39,261
	Total property, plant and equipment	5,423,611			5,369,418
	Less accumulated depreciation and amortization	(3,255,821		)	(3,162,942		)
	Total property, plant and equipment, net	$	2,167,790		$	2,206,476
	Depreciation expense was $124.1 million and $108.0 million for the three months ended March 31, 2015 and March 31, 2014, respectively.
	During 2013, we purchased land for a factory and research and development center in Korea ("K5") for $104.1 million. In 2014, we commenced construction activities and incurred costs of $29.8 million, including capitalized interest of $8.6 million, which is reflected in construction in progress. As of March 31, 2015, construction in progress reflects $49.9 million of costs, including capitalized interest of $10.8 million.

Investments

Investments	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments	12.    Investments
	Investments consist of the following:
		March 31,				December 31,
		2015				2014
		Carrying		Ownership		Carrying		Ownership
		Value		Interest		Value		Interest
		(In thousands)				(In thousands)
	Investment in unconsolidated affiliate	$	138,218	65.7	%	$	117,733	60	%
	J-Devices Corporation
	In October 2009, Amkor and Toshiba Corporation (“Toshiba”) invested in Nakaya Microdevices Corporation (“NMD”) and formed a joint venture to provide semiconductor packaging and test services in Japan. As a result of the transaction, NMD changed its name to J-Devices. We invested $16.7 million for our original 30% equity interest and options to acquire additional equity interests. We exercised our options and increased our ownership interest in J-Devices from 30% to 60% in April 2013, for an aggregate purchase price of $67.4 million, and from 60% to 65.7% in January 2015, for an aggregate purchase price of $12.9 million. J-Devices is now owned 65.7% by Amkor and 34.3% by the former shareholders of NMD.
	The remaining option is exercisable beginning in the fourth quarter of 2015 and each year thereafter and permits us to increase our ownership interest in J-Devices up to 80% by purchasing shares owned by the other shareholders. If exercised in 2015, we would expect closing to occur by early 2016. After we own 80% or more shares, the original shareholders of NMD have a put option which allows them to sell their shares to us. The exercise price for all options is payable in cash and is determined using a formula based on the net book value and a multiple of earnings before interest, taxes, depreciation and amortization of J-Devices.
	The governance provisions currently applicable to J-Devices restrict our ability, even with our majority ownership, to cause J-Devices to take certain actions without the consent of the other investors. Accordingly, we account for our investment in J-Devices using the equity method of accounting. Under the equity method of accounting, we recognize our proportionate share of J-Devices' net income or loss, which is after J-Devices' income taxes in Japan, during each accounting period as a change in our investment in unconsolidated affiliate. J-Devices' financial information is converted to U.S. GAAP and translated into U.S. dollars using Japanese yen as the functional currency. In addition, we record equity method adjustments as a change in our investment. The equity method adjustments include the amortization of basis differences as a result of the cost of our investment differing from our proportionate share of J-Devices' equity.
	On June 30, 2014, J-Devices purchased 100% of the shares of our wholly-owned subsidiary engaged in semiconductor packaging and test operations in Japan. For additional information regarding this transaction, we refer you to Note 3.

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Accrued Expenses	13.    Accrued Expenses
	Accrued expenses consist of the following:
		March 31,		December 31,
		2015		2014
		(In thousands)
	Payroll and benefits	$	62,626	$	77,635
	Deferred revenue and customer advances	59,171		56,829
	Income taxes payable	38,072		31,580
	Accrued interest	36,995		15,947
	Accrued settlement costs (Note 17)	31,006		32,414
	Accrued severance plan obligations (Note 15)	13,809		13,226
	Other accrued expenses	30,941		31,366
	Total accrued expenses	$	272,620	$	258,997
	Accrued settlement costs relate to amounts due as a result of the settlement of previously pending patent license litigation (Note 17).

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt	14.    Debt
	Following is a summary of short-term borrowings and long-term debt:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Debt of Amkor Technology, Inc.:
	Senior secured credit facilities:
	$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019	$	—		$	—
	Senior notes:
	7.375% Senior notes, due May 2018	345,000			345,000
	6.625% Senior notes, due June 2021, $75 million related party	400,000			400,000
	6.375% Senior notes, due October 2022	525,000			525,000
	Debt of subsidiaries:
	Amkor Technology Korea, Inc.:
	$41 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due June 2016 (1) (6)	30,000			—
	Term loan, LIBOR plus 3.70%, due June 2016 (2) (6)	70,000			70,000
	Term loan, foreign currency funding-linked base rate plus 1.80%, due March 2017 (3) (6)	80,000			80,000
	Term loan, LIBOR plus 3.70%, due July 2017 (1) (6)	—			30,000
	Term loan, foreign currency funding-linked base rate plus 1.75%, due September 2017 (4) (6)	—			5,000
	Term loan, LIBOR plus 3.70%, due December 2019 (5) (6)	70,000			70,000
	Other:
	Revolving credit facility, TAIFX plus a bank-determined spread, due April 2015 (Taiwan) (7)	—			—
		1,520,000			1,525,000
	Add: Unamortized premium	5,677			5,824
	Less: Short-term borrowings and current portion of long-term debt	(30,000		)	(5,000		)
	Long-term debt (including related party)	$	1,495,677		$	1,525,824
	-1	In June 2012, we entered into a $41.0 million revolving credit facility with a Korean Bank. Principal is payable at maturity. In February 2015, the facility was amended to lower the interest rate. In February 2015, we drew $30.0 million and used the proceeds to prepay our term loan due July 2017. In April 2015, the outstanding balance was repaid. Interest is due monthly, at a foreign currency funding-linked base rate plus 1.60% (3.05% as of March 31, 2015). As of March 31, 2015, $11.0 million was available to be borrowed for general working capital purposes.
	-2	In April 2013, we entered into a term loan agreement with a Korean bank pursuant to which we may borrow up to $150.0 million through April 2016 for general working capital purposes and the repayment of inter-company debt. Principal is payable at maturity. Interest is due quarterly, at a rate of LIBOR plus 3.70% (3.97% as of March 31, 2015). As of March 31, 2015, $80.0 million was available to be borrowed.
	-3	In March 2014, we entered into a term loan agreement with a Korean bank pursuant to which we borrowed $80.0 million. Principal is payable at maturity. In January 2015, the term loan was amended to lower the interest rate. Interest is due monthly, at a foreign currency funding-linked base rate plus 1.80% (3.08% as of March 31, 2015).
	-4	In March 2013, we entered into a loan agreement with a Korean bank pursuant to which we may borrow up to $150.0 million through September 2017. Principal is payable in quarterly installments of $5.0 million starting in December 2014, with the remaining balance due at maturity. Interest is due quarterly, at a foreign currency funding-linked base rate plus 1.75% (3.20% as of March 31, 2015). At March 31, 2015, $140.0 million was available to be borrowed for capital expenditures.
	-5	In November 2012, we entered into a loan agreement with a Korean bank pursuant to which we could borrow up to $100.0 million through March 2014. Principal is payable upon maturity. Interest is payable quarterly in arrears, at LIBOR plus 3.70% (3.94% as of March 31, 2015). In April 2015, the term loan was amended and now bears interest at LIBOR plus 2.70%.
	-6	The loans in Korea are collateralized by substantially all the land, factories and equipment located at our facilities in Korea.
	-7	In September 2012, Amkor Technology Taiwan Ltd, a subsidiary in Taiwan, entered into a revolving credit facility. Availability under the revolving credit facility was originally $44.0 million and subsequent availability steps down $5.0 million every six months from the original available balance. Principal is payable at maturity. As of March 31, 2015, $19.0 million was available to be drawn for general corporate purposes and capital expenditures.
	The debt of Amkor Technology, Inc. is structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries. The agreements governing our indebtedness contain a number of affirmative and negative covenants which restrict our ability to pay dividends and could restrict our operations. We have never paid a dividend to our stockholders and we do not have any present plans for doing so. We were in compliance with all of our covenants at March 31, 2015.

Pension_and_Severance_Plans

Pension and Severance Plans	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Pension and Severance Plans	15.    Pension and Severance Plans
	Foreign Defined Benefit Pension Plans
	Our subsidiaries in Japan, Malaysia, the Philippines and Taiwan sponsor defined benefit pension plans that cover substantially all of their respective employees who are not covered by statutory plans. Charges to expense are based upon actuarial analyses. The components of net periodic pension cost for these defined benefit plans are as follows:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Service cost	$	1,219		$	1,424
	Interest cost	766			779
	Expected return on plan assets	(856		)	(766		)
	Amortization of prior service cost	9			49
	Recognized actuarial loss	21			92
	Net periodic pension cost	$	1,159		$	1,578
	Korean Severance Plan
	Our subsidiary in Korea participates in an accrued severance plan that covers employees with at least one year of service. To the extent eligible employees are terminated, our subsidiary in Korea would be required to make lump-sum severance payments on behalf of these eligible employees based on their length of service, seniority and rate of pay at the time of termination. Accrued severance benefits are estimated assuming all eligible employees were to terminate their employment at the balance sheet date. Our contributions to the National Pension Plan of the Republic of Korea are deducted from accrued severance benefit liabilities.
	The provision recorded for severance benefits for the three months ended March 31, 2015 and 2014, was $5.1 million and $5.6 million, respectively. The balance of our Korean severance obligation consists of the following:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Current (Accrued expenses)	$	13,809		$	13,226
	Non-current (Pension and severance obligations)	133,701			133,435
	Total Korean severance obligation	$	147,510		$	146,661

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	16.    Fair Value Measurements
	The accounting framework for determining fair value includes a hierarchy for ranking the quality and reliability of the information used to measure fair value, which enables the reader of the financial statements to assess the inputs used to develop those measurements. The fair value hierarchy consists of three tiers as follows: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, model-based valuation techniques for which all significant assumptions are observable in the market or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities and Level 3, defined as unobservable inputs that are not corroborated by market data.
	The fair values of cash, accounts receivable, trade accounts payable, capital expenditures payable, and certain other current assets and accrued expenses approximate carrying values because of their short-term nature. The carrying value of other non-current liabilities approximates fair value. Our assets and liabilities recorded at fair value on a recurring basis include cash equivalent money market funds and restricted cash money market funds. Cash equivalent money market funds and restricted cash money market funds are invested in U.S. money market funds and various U.S. and foreign bank operating and time deposit accounts, which are due on demand or carry a maturity date of less than three months when purchased. No restrictions have been imposed on us regarding withdrawal of balances with respect to our cash equivalents as a result of liquidity or other credit market issues affecting the money market funds we invest in or the counterparty financial institutions holding our deposits. Money market funds are valued using quoted market prices in active markets for identical assets.
	Our recurring fair value measurements consist of the following:
		March 31,		December 31,
		2015		2014
		(In thousands)
	Cash equivalent money market funds (Level 1)	$	106,334	$	145,938
	Restricted cash money market funds (Level 1)	2,681		2,681
	We also measure certain assets and liabilities, including property, plant and equipment and our investment in J-Devices, at fair value on a nonrecurring basis.
	We measure the fair value of our debt for disclosure purposes. The following table presents the fair value of financial instruments that are not recorded at fair value on a recurring basis:
		March 31, 2015				December 31, 2014
		Fair		Carrying		Fair		Carrying
		Value		Value		Value		Value
		(In thousands)
	Senior notes (Level 1)	$	1,311,521	$	1,275,677	$	1,268,619	$	1,275,824
	Revolving credit facility and term loans (Level 2)	254,095		250,000		254,999		255,000
	Total debt	$	1,565,616	$	1,525,677	$	1,523,618	$	1,530,824
	The estimated fair value of our senior notes is based primarily on quoted market prices reported on or near the respective balance sheet dates. The estimated fair value of our revolving credit facility and term loans was calculated using a discounted cash flow analysis, which utilized market based assumptions including forward interest rates adjusted for credit risk.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	17.    Commitments and Contingencies
	We have a letter of credit sub-facility of $25.0 million under our $200.0 million senior secured revolving credit facility that matures in December 2019. As of March 31, 2015, we had $0.4 million of standby letters of credit outstanding. Such standby letters of credit are used in the ordinary course of our business and are collateralized by our cash balances.
	We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers' specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial.
	Legal Proceedings
	We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to make a determination as to the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. We believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future.
	In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.
	Proceedings with Tessera, Inc.
	We were involved in several legal proceedings with Tessera, Inc. (“Tessera”) related to a license agreement (the “License Agreement”) entered into in 1996 between Tessera and our predecessor. The proceedings generally involved disputes about whether or not Amkor owed Tessera royalties under the License Agreement with respect to certain packages, the termination of the License Agreement and post-termination infringement.
	In January 2015, the parties entered into a settlement agreement to end all pending proceedings related to the dispute. Under the terms of the settlement, Amkor agreed to pay Tessera a total of $155.0 million in 16 equal quarterly recurring payments commencing in the first quarter of 2015, and continuing through the fourth quarter of 2018, and the parties agreed to a mutual release and dismissal of all claims relating to their pending litigation and arbitration proceedings. The settlement agreement also provides that Tessera and Amkor will look for opportunities to engage in potential technology collaboration.
	In connection with the settlement, we recorded a pre-tax charge of $87.1 million for the three months ended December 31, 2014, of which $75.3 million was charged to cost of sales and $11.8 million was charged to interest expense. This charge reflects the aggregate amount due under the settlement agreement, net of amounts previously reserved. At March 31, 2015, the total liability owed Tessera is $145.3 million of which $31.0 million is a current liability, $98.5 million is a non-current liability and $15.8 million will be imputed into interest over time.

Interim_Financial_Statements_P

Interim Financial Statements (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The Consolidated Financial Statements and related disclosures as of March 31, 2015, and for the three months ended March 31, 2015 and 2014, are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2014, Consolidated Balance Sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S.”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. In our opinion, these financial statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods. These financial statements should be read in conjunction with the financial statements included in our Annual Report for the year ended December 31, 2014, filed on Form 10-K with the SEC on February 19, 2015. The results of operations for the three months ended March 31, 2015, are not necessarily indicative of the results to be expected for the full year. Unless the context otherwise requires, all references to “Amkor,” “we,” “us,” “our” or the “company” are to Amkor Technology, Inc. and our subsidiaries.
	On June 30, 2014, we completed the sale of our Japanese subsidiary to J-Devices, our equity-method joint venture in Japan. The financial results of the entity were included in our consolidated financial statements up to the date of sale (Note 3) and have subsequently been included in the results of J-Devices.
	The U.S. dollar is our reporting currency and the functional currency for our subsidiaries. Effective June 30, 2014, we changed the functional currency for our sales office in Japan to the U.S. dollar primarily due to an increase in the mix of our U.S. dollar denominated sales. The change in functional currency is applied on a prospective basis.
Use of Estimates	The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments.

ShareBased_Compensation_Plans_

Share-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of all common stock option activity	The following table summarizes our stock option activity for the three months ended March 31, 2015:
		Number of			Weighted Average				Weighted Average	Aggregate
		Shares			Exercise Price				Remaining	Intrinsic
		(In thousands)			Per Share				Contractual	Value
									Term (Years)	(In thousands)
	Outstanding at December 31, 2014	3,822			$	6.25
	Granted	100			8.92
	Exercised	(119	)		4.81
	Forfeited or expired	(69	)		4.28
	Outstanding at March 31, 2015	3,734			$	6.41			6.22	$	10,424
	Fully vested at March 31, 2015 and expected to vest thereafter	3,706			$	6.41			6.21	$	10,329
	Exercisable at March 31, 2015	2,244			$	7			4.83	$	5,330
Assumptions used in valuing the weighted average fair values of the options granted	The following assumptions were used to calculate the weighted average fair values of the options granted:
		For the Three Months Ended
		March 31,
		2015				2014
	Expected life (in years)	6.1				6.1
	Risk-free interest rate	1.7		%		1.9		%
	Volatility	50		%		59		%
	Dividend yield	—				—
	Weighted average grant date fair value per option granted	$	4.38			$	2.89
Restricted share activity	The following table summarizes our restricted share activity for the three months ended March 31, 2015:
		Number of			Weighted
		Shares			Average
		(In thousands)			Grant-Date
					Fair Value
					(Per share)
	Nonvested at December 31, 2014	660			$	4.58
	Awards granted	8			9.85
	Awards vested	(89	)		5.27
	Awards forfeited	(17	)		4.46
	Nonvested at March 31, 2015	562			$	4.55

Other_Income_and_Expense_Table

Other Income and Expense (Tables)	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
Schedule of Other Nonoperating Income (Expense) [Table Text Block]	Other income and expense consists of the following:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Interest income	$	(983	)	$	(711	)
	Foreign currency loss, net	207			334
	Other expense, net	278			413
	Total other (income) expense, net	$	(498	)	$	36

Earnings_Per_Share_Earnings_Pe

Earnings Per Share Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per share	The following table summarizes the computation of basic and diluted EPS:
		For the Three Months Ended
		March 31,
		2015				2014
		(In thousands,
		except per share data)
	Net income attributable to Amkor	$	28,781			$	20,633
	Income allocated to participating securities	(68		)		(105		)
	Net income available to Amkor common stockholders — basic	28,713				20,528
	Adjustment for dilutive securities on net income:
	Net income reallocated to participating securities	—				3
	Interest on 6.0% convertible notes due 2014, net of tax	—				907
	Net income attributable to Amkor — diluted	$	28,713			$	21,438
	Weighted average shares outstanding — basic	236,708				216,757
	Effect of dilutive securities:
	Stock options	716				109
	6.0% convertible notes due 2014	—				18,631
	Weighted average shares outstanding — diluted	237,424				235,497
	Net income attributable to Amkor per common share:
	Basic	$	0.12			$	0.09
	Diluted	0.12				0.09
Antidilutive effect of potential shares of common stock that were excluded from diluted earnings per share	The following table summarizes the potential shares of common stock that were excluded from diluted EPS, because the effect of including these potential shares was antidilutive:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Stock options and restricted share awards	1,400			4,265

Equity_and_Accumulated_Other_C1

Equity and Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Changes in equity attributable to both Company and noncontrolling interests	The following tables reflect the changes in equity attributable to both Amkor and the noncontrolling interests:
		Attributable			Attributable to			Total
		to Amkor			Noncontrolling
					Interests
		(In thousands)
	Equity at December 31, 2014	$	1,116,235		$	14,701		$	1,130,936
	Net income	28,781			916			29,697
	Other comprehensive income	1,238			—			1,238
	Issuance of stock through employee share-based compensation plans	574			—			574
	Treasury stock acquired through surrender of shares for tax withholding	(230		)	—			(230		)
	Share-based compensation expense	1,369			—			1,369
	Equity at March 31, 2015	$	1,147,967		$	15,617		$	1,163,584
		Attributable			Attributable to			Total
		to Amkor			Noncontrolling
					Interests
		(In thousands)
	Equity at December 31, 2013	$	953,740		$	11,200		$	964,940
	Net income	20,633			550			21,183
	Other comprehensive income	3,949			—			3,949
	Issuance of stock through employee share-based compensation plans	438			—			438
	Treasury stock acquired through surrender of shares for tax withholding	(122		)	—			(122		)
	Share-based compensation expense	972			—			972
	Equity at March 31, 2014	$	979,610		$	11,750		$	991,360
Schedule of Accumulated Other Comprehensive Income	The following tables reflect the changes in accumulated other comprehensive income (loss), net of tax:
		Defined Benefit Pension			Foreign Currency Translation			Equity Interest in J-Devices' Other Comprehensive Income (Loss)			Total
		(In thousands)
	Accumulated other comprehensive loss at	$	(2,525	)	$	(513	)	$	(29,829	)	$	(32,867	)
	31-Dec-14
	Other comprehensive (loss) income before reclassifications	—			(122		)	1,338			1,216
	Amounts reclassified from accumulated other comprehensive loss	22			—			—			22
	Other comprehensive income (loss)	22			(122		)	1,338			1,238
	Accumulated other comprehensive loss at	$	(2,503	)	$	(635	)	$	(28,491	)	$	(31,629	)
	31-Mar-15
		Defined Benefit Pension			Foreign Currency Translation			Equity Interest in J-Devices' Other Comprehensive Income (Loss)			Total
		(In thousands)
	Accumulated other comprehensive (loss) income at	$	(1,013	)	$	11,451		$	(10,693	)	$	(255	)
	31-Dec-13
	Other comprehensive income before reclassifications	—			685			3,144			3,829
	Amounts reclassified from accumulated other comprehensive (loss) income	120			—			—			120
	Other comprehensive income	120			685			3,144			3,949
	Accumulated other comprehensive (loss) income at	$	(893	)	$	12,136		$	(7,549	)	$	3,694
	31-Mar-14

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories consist of the following:
		March 31,		December 31, 2014
		2015
		(In thousands)
	Raw materials and purchased components	$	162,250	$	161,942
	Work-in-process	65,355		61,437
	Total inventories	$	227,605	$	223,379

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Summary of Property, plant and equipment	Property, plant and equipment consist of the following:
		March 31,			December 31, 2014
		2015
		(In thousands)
	Land	$	207,985		$	207,985
	Land use rights	26,845			26,845
	Buildings and improvements	944,246			940,846
	Machinery and equipment	3,977,069			3,953,891
	Software and computer equipment	186,868			185,243
	Furniture, fixtures and other equipment	16,274			15,347
	Construction in progress	64,324			39,261
	Total property, plant and equipment	5,423,611			5,369,418
	Less accumulated depreciation and amortization	(3,255,821		)	(3,162,942		)
	Total property, plant and equipment, net	$	2,167,790		$	2,206,476

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments	Investments consist of the following:
		March 31,				December 31,
		2015				2014
		Carrying		Ownership		Carrying		Ownership
		Value		Interest		Value		Interest
		(In thousands)				(In thousands)
	Investment in unconsolidated affiliate	$	138,218	65.7	%	$	117,733	60	%

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2015
Payables and Accruals [Abstract]
Summarized Accrued expenses	Accrued expenses consist of the following:
		March 31,		December 31,
		2015		2014
		(In thousands)
	Payroll and benefits	$	62,626	$	77,635
	Deferred revenue and customer advances	59,171		56,829
	Income taxes payable	38,072		31,580
	Accrued interest	36,995		15,947
	Accrued settlement costs (Note 17)	31,006		32,414
	Accrued severance plan obligations (Note 15)	13,809		13,226
	Other accrued expenses	30,941		31,366
	Total accrued expenses	$	272,620	$	258,997

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of Short term Borrowings And Long term Debt	Following is a summary of short-term borrowings and long-term debt:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Debt of Amkor Technology, Inc.:
	Senior secured credit facilities:
	$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019	$	—		$	—
	Senior notes:
	7.375% Senior notes, due May 2018	345,000			345,000
	6.625% Senior notes, due June 2021, $75 million related party	400,000			400,000
	6.375% Senior notes, due October 2022	525,000			525,000
	Debt of subsidiaries:
	Amkor Technology Korea, Inc.:
	$41 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due June 2016 (1) (6)	30,000			—
	Term loan, LIBOR plus 3.70%, due June 2016 (2) (6)	70,000			70,000
	Term loan, foreign currency funding-linked base rate plus 1.80%, due March 2017 (3) (6)	80,000			80,000
	Term loan, LIBOR plus 3.70%, due July 2017 (1) (6)	—			30,000
	Term loan, foreign currency funding-linked base rate plus 1.75%, due September 2017 (4) (6)	—			5,000
	Term loan, LIBOR plus 3.70%, due December 2019 (5) (6)	70,000			70,000
	Other:
	Revolving credit facility, TAIFX plus a bank-determined spread, due April 2015 (Taiwan) (7)	—			—
		1,520,000			1,525,000
	Add: Unamortized premium	5,677			5,824
	Less: Short-term borrowings and current portion of long-term debt	(30,000		)	(5,000		)
	Long-term debt (including related party)	$	1,495,677		$	1,525,824
	-1	In June 2012, we entered into a $41.0 million revolving credit facility with a Korean Bank. Principal is payable at maturity. In February 2015, the facility was amended to lower the interest rate. In February 2015, we drew $30.0 million and used the proceeds to prepay our term loan due July 2017. In April 2015, the outstanding balance was repaid. Interest is due monthly, at a foreign currency funding-linked base rate plus 1.60% (3.05% as of March 31, 2015). As of March 31, 2015, $11.0 million was available to be borrowed for general working capital purposes.
	-2	In April 2013, we entered into a term loan agreement with a Korean bank pursuant to which we may borrow up to $150.0 million through April 2016 for general working capital purposes and the repayment of inter-company debt. Principal is payable at maturity. Interest is due quarterly, at a rate of LIBOR plus 3.70% (3.97% as of March 31, 2015). As of March 31, 2015, $80.0 million was available to be borrowed.
	-3	In March 2014, we entered into a term loan agreement with a Korean bank pursuant to which we borrowed $80.0 million. Principal is payable at maturity. In January 2015, the term loan was amended to lower the interest rate. Interest is due monthly, at a foreign currency funding-linked base rate plus 1.80% (3.08% as of March 31, 2015).
	-4	In March 2013, we entered into a loan agreement with a Korean bank pursuant to which we may borrow up to $150.0 million through September 2017. Principal is payable in quarterly installments of $5.0 million starting in December 2014, with the remaining balance due at maturity. Interest is due quarterly, at a foreign currency funding-linked base rate plus 1.75% (3.20% as of March 31, 2015). At March 31, 2015, $140.0 million was available to be borrowed for capital expenditures.
	-5	In November 2012, we entered into a loan agreement with a Korean bank pursuant to which we could borrow up to $100.0 million through March 2014. Principal is payable upon maturity. Interest is payable quarterly in arrears, at LIBOR plus 3.70% (3.94% as of March 31, 2015). In April 2015, the term loan was amended and now bears interest at LIBOR plus 2.70%.
	-6	The loans in Korea are collateralized by substantially all the land, factories and equipment located at our facilities in Korea.
	-7	In September 2012, Amkor Technology Taiwan Ltd, a subsidiary in Taiwan, entered into a revolving credit facility. Availability under the revolving credit facility was originally $44.0 million and subsequent availability steps down $5.0 million every six months from the original available balance. Principal is payable at maturity. As of March 31, 2015, $19.0 million was available to be drawn for general corporate purposes and capital expenditures.
	The

Pension_and_Severance_Plans_Ta

Pension and Severance Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Components of net periodic pension cost	The components of net periodic pension cost for these defined benefit plans are as follows:
		For the Three Months Ended
		March 31,
		2015			2014
		(In thousands)
	Service cost	$	1,219		$	1,424
	Interest cost	766			779
	Expected return on plan assets	(856		)	(766		)
	Amortization of prior service cost	9			49
	Recognized actuarial loss	21			92
	Net periodic pension cost	$	1,159		$	1,578
Schedule of Korean severance obligation	The balance of our Korean severance obligation consists of the following:
		March 31,			December 31,
		2015			2014
		(In thousands)
	Current (Accrued expenses)	$	13,809		$	13,226
	Non-current (Pension and severance obligations)	133,701			133,435
	Total Korean severance obligation	$	147,510		$	146,661

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Valuation of money market funds and restricted cash using quoted market prices in active markets for identical assets	Our recurring fair value measurements consist of the following:
		March 31,		December 31,
		2015		2014
		(In thousands)
	Cash equivalent money market funds (Level 1)	$	106,334	$	145,938
	Restricted cash money market funds (Level 1)	2,681		2,681
Financial instruments that are not recorded at fair value	The following table presents the fair value of financial instruments that are not recorded at fair value on a recurring basis:
		March 31, 2015				December 31, 2014
		Fair		Carrying		Fair		Carrying
		Value		Value		Value		Value
		(In thousands)
	Senior notes (Level 1)	$	1,311,521	$	1,275,677	$	1,268,619	$	1,275,824
	Revolving credit facility and term loans (Level 2)	254,095		250,000		254,999		255,000
	Total debt	$	1,565,616	$	1,525,677	$	1,523,618	$	1,530,824

Sale_of_Subsidiary_to_JDevices1

Sale of Subsidiary to J-Devices (Details)	3 Months Ended	1 Months Ended		3 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Mar. 31, 2015	Mar. 31, 2015
	J-Devices [Member]	Amkor Iwate Company Ltd [Member]	Amkor Iwate Company Ltd [Member]	Amkor Iwate Company Ltd [Member]	Amkor Iwate Company Ltd [Member]	Amkor Iwate Company Ltd [Member]
	USD ($)	USD ($)	JPY (¥)	USD ($)	USD ($)	JPY (¥)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of Stock, Percentage of Ownership before Transaction		100.00%	100.00%
Significant Acquisitions and Disposals, Acquisition Costs or Sale Proceeds		$9.50	¥ 1,100	$9.50
Proceeds from Divestiture of Interest in Consolidated Subsidiaries		1	100
Proceeds to Be Received from Divestiture of Interest in Consolidated Subsidiaries					8.5	1,000
Gain (Loss) on Disposition of Business				9.2
Disposal Group, Including Discontinued Operation, Foreign Currency Translation Gains (Losses)				12.6
Business Combination, Bargain Purchase, Gain Recognized, Amount	14.7
Proportionate Share Of Investee Bargain Purchase Gain	8.8
Combined Net Gain from Sale of Subsidiary				$18

ShareBased_Compensation_Plans_1

Share-Based Compensation Plans Compensation Expense (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense	$1,369	$972

ShareBased_Compensation_Plans_2

Share-Based Compensation Plans Stock Options (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding beginning balance	3,822
Weighted average exercise price per share outstanding beginning balance	$6.25
Number of shares granted	100
Weighted average exercise price per share granted	$8.92
Number of shares exercised	-119
Weighted average exercise price per share exercised	$4.81
Number of shares forfeited or expired	-69
Weighted average exercise price per share forfeited or expired	$4.28
Number of shares outstanding ending balance	3,734
Weighted average exercise price per share outstanding ending balance	$6.41
Weighted average exercise price per share average contractual term (years)	6 years 2 months 19 days
Aggregate intrinsic value outstanding ending balance (in dollars)	$10,424
Number of shares fully vested and expected to vest	3,706
Weighted average exercise price per share fully vested and expected to vest	$6.41
Weighted average remaining contractual term fully vested and expected to vest (years)	6 years 2 months 16 days
Aggregate intrinsic value fully vested and expected to vest (in dollars)	10,329
Number of shares exercisable	2,244
Weighted average exercise price per share exercisable	$7
Weighted average remaining contractual term exercisable (years)	4 years 9 months 29 days
Aggregate intrinsic value exercisable (in dollars)	$5,330

ShareBased_Compensation_Plans_3

Share-Based Compensation Plans Weighted Average Fair Value (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (in years)	6 years 1 month 6 days	6 years 1 month 6 days
Risk-free interest rate	1.70%	1.90%
Volatility	50.00%	59.00%
Dividend yield	0.00%	0.00%
Weighted average grant date fair value per option granted (in dollars per share)	$4.38	$2.89

ShareBased_Compensation_Plans_4

Share-Based Compensation Plans Restricted Shares (Details) (Restricted shares [Member], USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015
Restricted shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares nonvested beginning balance	660
Weighted average grant-date fair value nonvested beginning balance (in dollars per share)	$4.58
Number of shares awards granted	8
Weighted average grant-date fair value awards granted (in dollars per share)	$9.85
Number of shares awards vested	-89
Weighted average grant-date fair value awards vested (in dollars per share)	$5.27
Number of shares awards forfeited	-17
Weighted average grant-date fair value awards forfeited (in dollars per share)	$4.46
Number of shares nonvested ending balance	562
Weighted average grant-date fair value nonvested ending balance (in dollars per share)	$4.55

ShareBased_Compensation_Plans_5

Share-Based Compensation Plans Textuals (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense from share-based compensation awards	$3.60
Weighted-average period of recognition of unrecognized compensation expense (in years)	2 years 3 months 10 days
Restricted shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense from share-based compensation awards	$2.20
Weighted-average period of recognition of unrecognized compensation expense (in years)	1 year 11 months 20 days

Other_Income_and_Expense_Detai

Other Income and Expense (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Income and Expenses [Abstract]
Interest income	($983)	($711)
Foreign currency loss, net	207	334
Other expense, net	278	413
Total other (income) expense, net	($498)	$36

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense	$5,999	$4,929

Income_Taxes_Unrecognized_Tax_

Income Taxes Unrecognized Tax Benefits (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits	$12.70	$12.70

Earnings_Per_Share_Earnings_Pe1

Earnings Per Share Earnings Per Share (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Dilutive Securities Adjustments [Line Items]
Net income attributable to Amkor	$28,781	$20,633
Income allocated to participating securities	68	105
Net income available to Amkor common stockholders — basic	28,713	20,528
Adjustment for dilutive securities on net income:
Net income reallocated to participating securities	0	3
Net income attributable to Amkor — diluted	28,713	21,438
Weighted average shares outstanding — basic	236,708	216,757
Effect of dilutive securities:
Weighted average shares outstanding — diluted	237,424	235,497
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$0.12	$0.09
Diluted (in dollars per share)	$0.12	$0.09
Convertible Senior Subordinated Notes Due April 2014 [Member]
Adjustment for dilutive securities on net income:
Interest on 6.0% convertible notes due 2014, net of tax	$0	$907
Effect of dilutive securities:
6.0% convertible notes due 2014	0	18,631
Net income attributable to Amkor per common share:
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Stock Options Dilutive Effect [Member]
Effect of dilutive securities:
Stock options	716	109

Earnings_Per_Share_Antidilutiv

Earnings Per Share Antidilutive (Details) (Stock Options And Restricted Shares [Member])	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Stock Options And Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted share awards	1,400	4,265

Equity_and_Accumulated_Other_C2

Equity and Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	$1,130,936	$964,940
Net income	29,697	21,183
Other comprehensive income (loss)	1,238	3,949
Issuance of stock through employee share-based compensation plans	574	438
Treasury stock acquired through surrender of shares for tax withholding	-230	-122
Share-based compensation expense	1,369	972
Equity, Ending balance	1,163,584	991,360
Amkor [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	1,116,235	953,740
Net income	28,781	20,633
Other comprehensive income (loss)	1,238	3,949
Issuance of stock through employee share-based compensation plans	574	438
Treasury stock acquired through surrender of shares for tax withholding	-230	-122
Share-based compensation expense	1,369	972
Equity, Ending balance	1,147,967	979,610
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning balance	14,701	11,200
Net income	916	550
Other comprehensive income (loss)	0	0
Issuance of stock through employee share-based compensation plans	0	0
Treasury stock acquired through surrender of shares for tax withholding	0	0
Share-based compensation expense	0	0
Equity, Ending balance	$15,617	$11,750

Equity_and_Accumulated_Other_C3

Equity and Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	($32,867)	($255)
Other comprehensive income (loss) before reclassifications	1,216	3,829
Amounts reclassified from accumulated other comprehensive (loss) income	22	120
Total other comprehensive income	1,238	3,949
Accumulated other comprehensive (loss) income, ending balance	-31,629	3,694
Defined Benefit Pension [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	-2,525	-1,013
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	22	120
Total other comprehensive income	22	120
Accumulated other comprehensive (loss) income, ending balance	-2,503	-893
Foreign Currency Translation [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	-513	11,451
Other comprehensive income (loss) before reclassifications	-122	685
Amounts reclassified from accumulated other comprehensive (loss) income	0	0
Total other comprehensive income	-122	685
Accumulated other comprehensive (loss) income, ending balance	-635	12,136
Equity Interest in J-Devices' Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive (loss) income, beginning balance	-29,829	-10,693
Other comprehensive income (loss) before reclassifications	1,338	3,144
Amounts reclassified from accumulated other comprehensive (loss) income	0	0
Total other comprehensive income	1,338	3,144
Accumulated other comprehensive (loss) income, ending balance	($28,491)	($7,549)

Factoring_of_Accounts_Receivab1

Factoring of Accounts Receivable (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Total Factored [Member]
Accounts Receivable Sold without Recourse [Line Items]
Accounts Receivable Sold without Recourse	$81.30	$69
Factoring Fees [Member]
Accounts Receivable Sold without Recourse [Line Items]
Accounts Receivable Sold without Recourse	$0.40	$0.30

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventories
Raw materials and purchased components	$162,250	$161,942
Work-in-process	65,355	61,437
Total inventories	$227,605	$223,379

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$5,423,611	$5,369,418
Less accumulated depreciation and amortization	-3,255,821	-3,162,942
Total property, plant and equipment, net	2,167,790	2,206,476
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	207,985	207,985
Land use rights [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,845	26,845
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	944,246	940,846
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,977,069	3,953,891
Software and computer equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	186,868	185,243
Furniture, fixtures and other equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	16,274	15,347
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$64,324	$39,261

Property_Plant_and_Equipment_N

Property, Plant and Equipment (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total depreciation expense	$124,100,000	$108,000,000
Property, Plant and Equipment, Gross	5,423,611,000		5,369,418,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	207,985,000		207,985,000
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	64,324,000		39,261,000
K5 Factory [Member] | Land [Member] | KOREA, REPUBLIC OF
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	104,100,000		104,100,000
K5 Factory [Member] | Construction in Progress [Member] | KOREA, REPUBLIC OF
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	49,900,000		29,800,000
Accumulated Capitalized Interest Costs	$10,800,000		$8,600,000

Investments_Details

Investments (Details) (USD $)	Mar. 31, 2015	Jan. 31, 2015	Dec. 31, 2014	Apr. 30, 2013	Mar. 31, 2013
In Thousands, unless otherwise specified
Schedule of Equity Method Investments [Line Items]
Carrying value	$138,218		$117,733
J-Devices [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value	$138,218		$117,733
Ownership interest	65.70%	65.70%	60.00%	60.00%	30.00%

Investments_Narrative_Details

Investments Narrative (Details) (USD $)	3 Months Ended		1 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jan. 31, 2015	Apr. 30, 2013	Oct. 31, 2009	Jun. 30, 2014	Dec. 31, 2014	Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Businesses and Interest in Affiliates	$12,908	$0
J-Devices [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	65.70%		65.70%	60.00%			60.00%	30.00%
Payments to Acquire Businesses and Interest in Affiliates			$12,900	$67,400	$16,700
Ownership Threshold 2015 [Member] | J-Devices [Member]
Schedule of Equity Method Investments [Line Items]
Maximum ownership ratio of call options	80.00%
Minimum ownership threshold, put option	80.00%
Former NMD Shareholders [Member] | J-Devices [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	34.30%
Japanese Subsidiary [Member]
Schedule of Equity Method Investments [Line Items]
Sale of Stock, Percentage of Ownership before Transaction						100.00%

Accrued_Expenses_Details

Accrued Expenses (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Payroll and benefits	$62,626	$77,635
Deferred revenue and customer advances	59,171	56,829
Income taxes payable	38,072	31,580
Accrued interest	36,995	15,947
Accrued settlement costs (Note 17)	31,006	32,414
Accrued severance plan obligations (Note 15)	13,809	13,226
Other accrued expenses	30,941	31,366
Total accrued expenses	$272,620	$258,997

Debt_Long_Term_Debt_Details

Debt Long Term Debt (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$1,520,000	$1,525,000
Add: Unamortized premium	5,677	5,824
Less: Short-term borrowings and current portion of long-term debt	-30,000	-5,000
Long-term debt (including related party)	1,495,677	1,525,824
$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	0	0
7.375% Senior notes, due May 2018 | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	345,000	345,000
6.625% Senior notes, due June 2021, $75 million related party | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	400,000	400,000
6.375% Senior notes, due October 2022 | Senior notes (Level 1)
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	525,000	525,000
KOREA, REPUBLIC OF | Revolving credit facility due June 2016 [Member] | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	30,000	0
KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due June 2016 (2) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	70,000	70,000
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.80%, due March 2017 (3) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	80,000	80,000
KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due July 2017 (1) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	0	30,000
KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.75%, due September 2017 (4) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	0	5,000
KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due December 2019 (5) | Subsidiary Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	70,000	70,000
TAIWAN, PROVINCE OF CHINA | Revolving credit facility, TAIFX plus a bank-determined spread, due April 2015 (Taiwan) (6) | Revolving Credit Facility [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt Including Related Party, Gross	$0	$0

Debt_Details

Debt (Details) (USD $)	3 Months Ended		1 Months Ended	3 Months Ended	1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 28, 2015	Sep. 30, 2012	Apr. 30, 2015	Apr. 30, 2013	Mar. 31, 2013	Nov. 30, 2012	Jun. 30, 2012
Debt Instrument [Line Items]
Borrowings under revolving credit facilities	$30,000,000	$0
Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due June 2016 (2)
Debt Instrument [Line Items]
Credit facility, borrowing capacity						150,000,000
Debt Instrument, Basis Spread on Variable Rate	3.70%
Debt, interest rate description	LIBOR plus 3.70%
Total effective rate (percentage)	3.97%
Current borrowing capacity	80,000,000
Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.80%, due March 2017 (3)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.80%
Debt, interest rate description	foreign currency funding-linked base rate plus 1.80%
Debt Instrument, Unused Borrowing Capacity, Amount		80,000,000
Total effective rate (percentage)	3.08%
Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due July 2017 (1)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.70%
Debt, interest rate description	LIBOR plus 3.70%
Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, foreign currency funding-linked base rate plus 1.75%, due September 2017 (4)
Debt Instrument [Line Items]
Credit facility, borrowing capacity							150,000,000
Debt Instrument, Basis Spread on Variable Rate	1.75%
Debt Instrument, Periodic Payment, Principal	5,000,000
Debt, interest rate description	foreign currency funding-linked base rate plus 1.75%
Total effective rate (percentage)	3.20%
Current borrowing capacity	140,000,000
Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due December 2019 (5)
Debt Instrument [Line Items]
Credit facility, borrowing capacity								100,000,000
Debt Instrument, Basis Spread on Variable Rate	3.70%
Debt, interest rate description	LIBOR plus 3.70%
Total effective rate (percentage)	3.94%
Senior notes (Level 1) | 7.375% Senior notes, due May 2018
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.38%
Senior notes (Level 1) | 6.625% Senior notes, due June 2021, $75 million related party
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.63%
Face amount for related party	75,000,000
Senior notes (Level 1) | 6.375% Senior notes, due October 2022
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.38%
Revolving Credit Facility [Member] | Line of Credit [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019
Debt Instrument [Line Items]
Credit facility, borrowing capacity	200,000,000
Debt, interest rate description	LIBOR plus 1.25%-1.75%
Revolving Credit Facility [Member] | Line of Credit [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Revolving Credit Facility [Member] | Line of Credit [Member] | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Revolving Credit Facility [Member] | Line of Credit [Member] | KOREA, REPUBLIC OF | Revolving credit facility due June 2016 [Member]
Debt Instrument [Line Items]
Credit facility, borrowing capacity	41,000,000								41,000,000
Debt Instrument, Basis Spread on Variable Rate	1.60%
Debt, interest rate description	foreign currency funding-linked base rate plus 1.60%
Borrowings under revolving credit facilities			30,000,000
Total effective rate (percentage)	3.05%
Current borrowing capacity	11,000,000
Revolving Credit Facility [Member] | Line of Credit [Member] | TAIWAN, PROVINCE OF CHINA | Revolving credit facility, TAIFX plus a bank-determined spread, due April 2015 (Taiwan) (6)
Debt Instrument [Line Items]
Credit facility, borrowing capacity	44,000,000
Debt, interest rate description	TAIFX plus a bank-determined spread
Current borrowing capacity	19,000,000
Line of Credit Facility, Step Down Provision	$5,000,000
Line of Credit Facility, Step Down Provision, Step Down Period				6 months
Subsequent Event [Member] | Subsidiary Term Loans [Member] | KOREA, REPUBLIC OF | Term loan, LIBOR plus 3.70%, due December 2019 (5)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate					2.70%

Pension_and_Severance_Plans_De

Pension and Severance Plans (Details) (Foreign Pension Plans [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Foreign Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$1,219	$1,424
Interest cost	766	779
Expected return on plan assets	-856	-766
Amortization of prior service cost	9	49
Recognized actuarial loss	21	92
Net periodic pension cost	$1,159	$1,578

Pension_and_Severance_Plans_Te

Pension and Severance Plans Textuals (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Non-current (Pension and severance obligations)	$153,027,000		$152,673,000
Korean Severance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Provision of Severance Benefits	5,100,000	5,600,000
Current (Accrued expenses)	13,809,000		13,226,000
Non-current (Pension and severance obligations)	133,701,000		133,435,000
Total Korean severance obligation	$147,510,000		$146,661,000
Minimum [Member] | Korean Severance Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accrued severance plan, minimum service period	1 year

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Measurements (Details) (Fair Value, Measurements, Recurring [Member], Fair Value, Inputs, Level 1 [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalent money market funds (Level 1)	$106,334	$145,938
Restricted cash money market funds (Level 1)	$2,681	$2,681

Fair_Value_Measurements_Fair_V1

Fair Value Measurements Fair Value of Debt (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$1,565,616	$1,523,618
Senior notes (Level 1) | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,311,521	1,268,619
Revolving credit facility and term loans (Level 2) | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	254,095	254,999
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,525,677	1,530,824
Carrying Value [Member] | Senior notes (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	1,275,677	1,275,824
Carrying Value [Member] | Revolving credit facility and term loans (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$250,000	$255,000

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	1 Months Ended	2 Months Ended	3 Months Ended
	Jan. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Estimated Litigation Liability, Current		$31,006,000	$32,414,000
Tessera Inc Legal Proceedings [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount	155,000,000	145,300,000
Number of Quarterly Settlement Payments	16
Litigation Settlement, Expense			87,100,000
Estimated Litigation Liability, Current		31,000,000
Estimated Litigation Liability, Noncurrent		98,500,000
Accrued settlement cost, unamortized interest		15,800,000
Cost of Sales [Member] | Tessera Inc Legal Proceedings [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Expense			75,300,000
Interest Expense [Member] | Tessera Inc Legal Proceedings [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Expense			11,800,000
Letter of Credit [Member]
Loss Contingencies [Line Items]
Credit facility, borrowing capacity		25,000,000
Available letter of credit subfacility utilized		400,000
$200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Line of Credit [Member] | Revolving Credit Facility [Member]
Loss Contingencies [Line Items]
Credit facility, borrowing capacity		$200,000,000