Amkor Technology (AMKR) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	AMKOR TECHNOLOGY, INC.
Entity Central Index Key	1,047,127
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		239,538,384

Consolidated Statements of Inco

Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net sales	$ 1,065,684	$ 1,008,385	$ 2,091,003	$ 1,907,669
Cost of sales	895,967	831,769	1,763,515	1,594,819
Gross profit	169,717	176,616	327,488	312,850
Selling, general and administrative	74,700	67,785	155,423	144,067
Research and development	41,076	44,281	82,005	85,849
Gain on sale of real estate	0	(108,109)	0	(108,109)
Total operating expenses	115,776	3,957	237,428	121,807
Operating income	53,941	172,659	90,060	191,043
Interest expense	21,127	22,158	41,138	43,412
Interest expense, related party	0	293	0	1,535
Other (income) expense, net	(11,001)	(3,288)	(7,569)	7,893
Total other expense, net	10,126	19,163	33,569	52,840
Income before taxes	43,815	153,496	56,491	138,203
Income tax expense	10,631	33,466	13,112	32,141
Net income	33,184	120,030	43,379	106,062
Net income attributable to non-controlling interests	(593)	(1,017)	(1,244)	(1,835)
Net income attributable to Amkor	$ 32,591	$ 119,013	$ 42,135	$ 104,227
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.14	$ 0.50	$ 0.18	$ 0.44
Diluted (in dollars per share)	$ 0.14	$ 0.50	$ 0.18	$ 0.44
Shares used in computing per common share amounts:
Basic (in shares)	239,351	238,863	239,283	238,774
Diluted (in shares)	239,804	239,679	239,805	239,601

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 33,184	$ 120,030	$ 43,379	$ 106,062
Other comprehensive income (loss), net of tax:
Adjustments to unrealized components of defined benefit pension plans	(42)	18	(81)	248
Foreign currency translation	(11,144)	(833)	3,947	12,753
Total other comprehensive income (loss)	(11,186)	(815)	3,866	13,001
Comprehensive income	21,998	119,215	47,245	119,063
Comprehensive income attributable to non-controlling interests	(593)	(1,017)	(1,244)	(1,835)
Comprehensive income attributable to Amkor	$ 21,405	$ 118,198	$ 46,001	$ 117,228

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 380,262	$ 596,364
Restricted cash	2,000	2,000
Accounts receivable, net of allowances	795,750	798,264
Inventories	243,019	213,649
Other current assets	37,148	33,727
Total current assets	1,458,179	1,644,004
Property, plant and equipment, net	2,754,960	2,695,065
Goodwill	25,472	25,036
Restricted cash	3,503	4,487
Other assets	139,567	139,796
Total assets	4,381,681	4,508,388
Current liabilities:
Short-term borrowings and current portion of long-term debt	115,057	123,848
Trade accounts payable	553,475	569,085
Capital expenditures payable	238,772	294,258
Accrued expenses	254,348	330,868
Total current liabilities	1,161,652	1,318,059
Long-term debt	1,214,535	1,240,581
Pension and severance obligations	184,072	182,216
Other non-current liabilities	51,264	47,823
Total liabilities	2,611,523	2,788,679
Commitments and contingencies (Note 16)
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; 285,322 and 285,129 shares issued; and 239,366 and 239,184 shares outstanding in 2018 and 2017, respectively	285	285
Additional paid-in capital	1,906,936	1,903,357
Retained earnings (accumulated deficit)	28,232	(13,903)
Accumulated other comprehensive income (loss)	26,385	22,519
Treasury stock, at cost, 45,956 and 45,945 shares, in 2018 and 2017, respectively	(216,087)	(215,982)
Total Amkor stockholders’ equity	1,745,751	1,696,276
Non-controlling interests in subsidiaries	24,407	23,433
Total equity	1,770,158	1,719,709
Total liabilities and equity	$ 4,381,681	$ 4,508,388

Consolidated Balance Sheets (U5

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Stockholders’ equity:
Preferred stock designated Series A, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock designated Series A, shares authorized	10,000,000	10,000,000
Preferred stock designated Series A, shares issued	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	285,322,000	285,129,000
Common stock, shares outstanding	239,366,000	239,184,000
Treasury stock, shares	45,956,000	45,945,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 43,379	$ 106,062
Depreciation and amortization	285,515	287,068
Gain on sale of real estate	0	(108,109)
Other operating activities and non-cash items	(3,239)	(4,659)
Changes in assets and liabilities	(119,276)	(80,403)
Net cash provided by operating activities	206,379	199,959
Cash flows from investing activities:
Payments for property, plant and equipment	(389,568)	(271,651)
Proceeds from sale of property, plant and equipment	603	130,962
Acquisition of business, net of cash acquired	0	(43,771)
Other investing activities	2,647	(2,117)
Net cash used in investing activities	(386,318)	(186,577)
Cash flows from financing activities:
Proceeds from revolving credit facilities	0	75,000
Proceeds from short-term debt	7,264	41,228
Payments of short-term debt	(31,546)	(32,110)
Proceeds from issuance of long-term debt	64,000	215,086
Payments of long-term debt	(77,015)	(207,653)
Payment of deferred consideration for purchase of facility	0	(3,890)
Payments of capital lease obligations	(1,689)	(2,665)
Other financing activities	492	561
Net cash provided by (used in) financing activities	(38,494)	85,557
Effect of exchange rate fluctuations on cash, cash equivalents and restricted cash	1,347	9,418
Net increase (decrease) in cash, cash equivalents and restricted cash	(217,086)	108,357
Cash, cash equivalents and restricted cash, beginning of period	602,851	555,495
Cash, cash equivalents and restricted cash, end of period	385,765	663,852
Non-cash investing and financing activities:
Property, plant and equipment included in capital expenditures payable	239,460	233,084
Equipment acquired through capital lease	$ 6,477	$ 929

Interim Financial Statements

Interim Financial Statements	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Interim Financial Statements	Interim Financial Statements Basis of Presentation. The Consolidated Financial Statements and related disclosures as of June 30, 2018 , and for the three and six months ended June 30, 2018 and 2017 , are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2017 , 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, 2017 , filed on Form 10-K with the SEC on February 23, 2018. The results of operations for the three and six months ended June 30, 2018 , 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. Effective January 1, 2018, we adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606) , using the full retrospective transition method as discussed in Note 2 . All amounts and disclosures set forth in this Form 10-Q reflect these changes. On May 22, 2017, we completed the purchase of Nanium, S.A. ("Nanium"). Nanium's financial results have been included in our Consolidated Financial Statements from the date of acquisition ( Note 4 ). 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. Goodwill. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation.

New Accounting Standards

New Accounting Standards	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
New Accounting Standards	New Accounting Standards Recently Adopted Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which was subsequently amended and clarified. The standard 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. The standard permits the use of either full retrospective or modified retrospective methods of adoption. Effective January 1, 2018, we adopted the requirements of Topic 606 using the full retrospective transition method. The new standard resulted in a change to the timing of revenue recognition, whereby revenue is recognized "over time" as services are performed rather than at a "point in time", generally upon shipment. The new standard also resulted in an increase in accounts receivables, net and a related decrease in inventories and deferred revenues. In accordance with Topic 606, we applied the following principles in connection with the adoption of the new standard: • We do not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less. • We do not adjust the promised amount of consideration for the effects of a significant financing component when we expect, at contract inception, that the period between when the entity transfers a promised good or service to a customer and when the customer pays for that good or service will be one year or less. • We exclude sales, use, value-added and similar taxes from the transaction price, without performing a jurisdiction-by-jurisdiction assessment. The adoption of the standard impacted our previously reported results as follows: For the Three Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 989,447 $ 18,938 $ 1,008,385 Cost of sales 817,212 14,557 831,769 Gross profit 172,235 4,381 176,616 Income tax expense 32,573 893 33,466 Net income 116,459 3,571 120,030 Net income attributable to Amkor 115,507 3,506 119,013 Net income attributable to Amkor per common share - diluted 0.48 0.02 0.50 For the Six Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 1,903,047 $ 4,622 $ 1,907,669 Cost of sales 1,587,906 6,913 1,594,819 Gross profit 315,141 (2,291 ) 312,850 Income tax expense 33,012 (871 ) 32,141 Net income 107,315 (1,253 ) 106,062 Net income attributable to Amkor 105,501 (1,274 ) 104,227 Net income attributable to Amkor per common share - diluted 0.44 — 0.44 December 31, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands) Balance Sheet: Accounts receivable, net $ 692,287 $ 105,977 $ 798,264 Inventories 326,492 (112,843 ) 213,649 Other assets 146,051 (6,255 ) 139,796 Accrued expenses 374,598 (43,730 ) 330,868 Other non-current liabilities 46,144 1,679 47,823 Accumulated deficit (1) (42,851 ) 28,948 (13,903 ) (1) The adjustment to accumulated deficit includes the 2017 and 2016 net income impact for the adoption of Topic 606 of $2.8 million and $11.3 million , respectively. The adjustment also includes the cumulative impact to our 2016 beginning accumulated deficit of $14.8 million . The adoption of the standard had no impact on cash provided by or used in operating, investing, or financing activities on our consolidated cash flow statements. In March 2017, the FASB issued ASU 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . ASU 2017-07 requires that the service cost component of net periodic pension costs be presented in the same line item as other compensation costs and all other components of net periodic pension costs be presented in the statement of income as nonoperating expenses. ASU 2017-07 is effective for reporting periods beginning after December 15, 2017 and applied retrospectively. We adopted ASU 2017-07 on January 1, 2018 and estimated the impact on the prior comparative period information presented in the consolidated financial statements applying the principles permitted by the standard. For the three and six months ended June 30, 2017 , the retrospective application resulted in a $(0.1) million and $0.2 million reclassification of pension costs from operating income to other (income) expense, net in the Consolidated Statements of Income for the respective periods. Refer to Note 14 for additional information. Recently Issued Standards In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which was subsequently amended and clarified. ASU 2016-02 requires a dual approach for lease accounting under which a lessee would account for leases as finance leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset, and for operating leases the lessee would recognize a straight-line lease expense. ASU 2016-02 is effective for reporting periods beginning after December 15, 2018 and requires either a modified retrospective transition approach with application in all comparative periods presented, or an alternative transition method, which permits a company to use its effective date as the date of initial application without restating comparative period financial statements. Early adoption is permitted. We are currently evaluating the impact that this guidance may have on our financial statements and disclosure, and have not yet selected a transition method.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Our significant accounting policies are detailed in Note 1 to our Consolidated Financial Statements in Part II, Item 8 of our Annual Report on Form 10-K for the year ended December 31, 2017. Significant changes to our accounting policies as a result of adopting Topic 606 are discussed below: Revenue Recognition . We recognize revenue, net of sales, use, value-added and other similar taxes, after the following: – A contract with a customer has been identified – All performance obligations within the customer contract have been identified – The transaction price attributable to the contract has been determined and allocated to each performance obligation, and – The performance obligations have been determined to be satisfied. Performance obligations are deemed to be satisfied when, or as, control of services has been transferred to the customer. Our packaging and test services are our performance obligations to our customers. Our packaging services include wafer bump, probe and assembly. We provide packaging and test services to our customers either individually or as part of a combined offering. In a combined offering, we account for the individual services separately if they are determined to be distinct. We determine a service to be distinct if it is separately identifiable from other services in the combined offering and if a customer can benefit from the unique service on its own or with other resources that are readily available to the customer. The consideration, including variable consideration, is allocated between the distinct services in a combined offering based upon the stand-alone selling prices of the individual services. Our services involve a high degree of specialization which are unique based on the design and purpose of the customer’s wafers. Accordingly, our negotiated pricing reflects the customized nature of our services and represents a customer-specific stand-alone selling price. We recognize revenue as services are rendered, which generally occurs over the course of two to three weeks. Services are generally billed at completion of each individual packaging or test service or in some instances at the completion of all services in a combined offering. We recognize revenue over time as services are rendered because our services create or enhance the customer’s wafer. We utilize an input method (cost incurred plus estimated margin) to determine the amount of revenue to recognize for in-process, but incomplete customer orders at a reporting date. During the period of providing our services, we generally do not control or take ownership of customers' wafers, nor do we include the cost of the wafer in our cost calculations. We believe that a cost-based input method is the most appropriate manner to measure how we satisfy our performance obligations to customers because the effort and costs incurred to package and/or test customer wafers are not linear over the duration of these services. Shipping and handling costs are accounted for as a cost to fulfill our performance obligations to customers. Accordingly, we record customer payments of shipping and handling costs as a component of net sales, and the costs incurred for shipping and handling are then charged to cost of sales. Unbilled Receivables . Unbilled receivables are revenues that have been recognized for performance obligations that have been satisfied, or partially satisfied, in advance of billing the customer. Revenue may be recognized in advance of billing as our contracts provide us with an unconditional right to consideration for work that is performed. Total unbilled receivables as of June 30, 2018 and December 31, 2017 were $106.6 million and $101.9 million , respectively. These amounts are included in accounts receivable, net of allowances in our Consolidated Balance Sheets. Inventories. Inventories consist of raw materials and purchased components, and are stated at the lower of cost and net realizable value. Cost is principally determined by standard cost or the weighted moving average method, both of which approximate actual cost. We review and set our standard costs as needed, but at a minimum on an annual basis. We reduce the carrying value of our inventories for the cost of inventory we estimate is excess and obsolete based on the age of our inventories. When a determination is made that the inventory will not be utilized in production or is not saleable, it is written-off.

Acquisition

Acquisition	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Acquisition	Acquisition On May 22, 2017, we completed the purchase of 100% of the shares of Nanium, a provider of wafer-level fan-out semiconductor packaging solutions. We allocated the purchase price to the assets acquired and liabilities assumed based on their estimated fair values on the date of acquisition. We did not record goodwill as a result of the acquisition.

Net Sales by Product Group and

Net Sales by Product Group and End Market	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Net Sales by Product Group and End Market	Net Sales by Product Group and End Market The following table presents net sales by product group: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) (In thousands) Advanced products (1) $ 496,241 $ 445,100 $ 971,993 $ 820,967 Mainstream products (2) 569,443 563,285 1,119,010 1,086,702 Total net sales $ 1,065,684 $ 1,008,385 $ 2,091,003 $ 1,907,669 (1) Advanced products include flip chip and wafer-level processing and related test services (2) Mainstream products include wirebond packaging and related test services The following table presents net sales by end market : For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 Communications (smartphones, tablets, handheld devices) 42 % 40 % 42 % 39 % Automotive, industrial and other (driver assist, infotainment, safety, performance) 26 % 27 % 26 % 28 % Computing (datacenter, infrastructure, PC/laptop, storage) 19 % 19 % 19 % 19 % Consumer (set-top boxes, televisions, connected home, personal electronics, visual imaging) 13 % 14 % 13 % 14 % Total net sales 100 % 100 % 100 % 100 %

Other Income and Expense

Other Income and Expense	6 Months Ended
	Jun. 30, 2018
Other Income and Expenses [Abstract]
Other Income and Expense	Other Income and Expense Other income and expense consists of the following: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Interest income $ (955 ) $ (955 ) $ (1,943 ) $ (1,466 ) Foreign currency (gain) loss, net (7,110 ) (2,252 ) (2,397 ) 9,132 Other (2,936 ) (81 ) (3,229 ) 227 Other (income) expense, net $ (11,001 ) $ (3,288 ) $ (7,569 ) $ 7,893

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In December 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was signed into law. Accounting Standards Codification ("ASC") 740, Income Taxes, requires companies to recognize the effect of tax law changes in the period of enactment even though the effective date for most provisions is for tax years beginning after December 31, 2017. Given the significance of the Tax Act, the SEC staff issued Staff Accounting Bulletin No. 118, which allows registrants to record provisional amounts during a one year “measurement period” similar to that used when accounting for business combinations. However, the measurement period is deemed to have ended earlier when the registrant has obtained, prepared and analyzed the information necessary to finalize its accounting. During the measurement period, impacts of the law are expected to be recorded at the time a reasonable estimate for all or a portion of the effects can be made, and provisional amounts can be recognized and adjusted as information becomes available, prepared or analyzed. We have reported provisional amounts for the income tax effects of the Tax Act for which the accounting is incomplete, but a reasonable estimate could be determined in our financial statements for the year ended December 31, 2017 . There were no specific impacts of the Tax Act that could not be reasonably estimated. Our estimate of the impact of the Tax Act may be adjusted throughout the allowable measurement period. We have not completed the accounting for any of the income tax effects of the Tax Act during the six months ended June 30, 2018 as we continue to collect additional information, prepare and analyze the information and evaluate any regulatory guidance or clarifications. We have not made adjustments to the provisional amounts reported for the year ended December 31, 2017, nor have we concluded on any accounting policy elections. Changes to our provisional estimates and further analysis could impact our judgments, elections and assertions. Income tax expense of $13.1 million for the six months ended June 30, 2018 reflects income taxes of our various operations, including foreign withholding taxes and minimum taxes. Income tax expense also reflects income taxed in foreign jurisdictions where we benefit from tax holidays. We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and results of recent operations. Except for deferred tax assets in Portugal, we consider it more likely than not that we will have sufficient taxable income to allow us to realize most of our foreign deferred tax assets. We maintain a valuation allowance on a portion of our U.S. net deferred tax assets, for net operating loss carryforwards not expected to be realized due to Global Intangible Low-Taxed Income ("GILTI") and foreign tax credit carryforwards expected to expire unused. Such valuation allowances are released as the related tax benefits are realized or when sufficient 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. Gross unrecognized tax benefits decreased from $27.2 million at December 31, 2017 , to $24.8 million as of June 30, 2018 . All of our unrecognized tax benefits would reduce our effective tax rate, if recognized. Our unrecognized tax benefits are subject to change for effective settlement of examinations, changes in the recognition threshold of tax positions, the expiration of statues of limitations and other factors. Tax return examinations involve uncertainties, and there can be no assurance that the outcome of examinations will be favorable.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	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 is reduced for treasury stock. Diluted EPS is computed based on the weighted-average number of common shares outstanding plus the effect of dilutive potential common shares outstanding during the period. Dilutive potential common shares include outstanding stock options and unvested restricted shares. The following table summarizes the computation of basic and diluted EPS: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands, except per share data) Net income attributable to Amkor common stockholders $ 32,591 $ 119,013 $ 42,135 $ 104,227 Weighted-average number of common shares outstanding — basic 239,351 238,863 239,283 238,774 Effect of dilutive securities: Stock options and restricted share awards 453 816 522 827 Weighted-average number of common shares outstanding — diluted 239,804 239,679 239,805 239,601 Net income attributable to Amkor per common share: Basic $ 0.14 $ 0.50 $ 0.18 $ 0.44 Diluted 0.14 0.50 0.18 0.44 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 anti-dilutive: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Stock options and restricted share awards 3,644 3,193 3,524 3,473

Equity and Accumulated Other Co

Equity and Accumulated Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Equity and Accumulated Other Comprehensive Income (Loss)	Equity and Accumulated Other Comprehensive Income (Loss) Changes in equity consist of the following: Attributable to Amkor Attributable to Non-controlling Interests Total (In thousands) Equity at December 31, 2017 $ 1,696,276 $ 23,433 $ 1,719,709 Net income 42,135 1,244 43,379 Other comprehensive income (loss) 3,866 — 3,866 Issuance of stock through employee share-based compensation plans 1,023 — 1,023 Treasury stock acquired through surrender of shares for tax withholding (105 ) — (105 ) Share-based compensation 2,556 — 2,556 Subsidiary dividends paid to non-controlling interests — (270 ) (270 ) Equity at June 30, 2018 $ 1,745,751 $ 24,407 $ 1,770,158 Attributable to Amkor Attributable to Non-controlling Interests Total (In thousands) Equity at December 31, 2016 $ 1,409,692 $ 19,825 $ 1,429,517 Net income 104,227 1,835 106,062 Other comprehensive income (loss) 13,001 — 13,001 Issuance of stock through employee share-based compensation plans 2,365 — 2,365 Treasury stock acquired through surrender of shares for tax withholding (1,378 ) — (1,378 ) Share-based compensation 2,516 — 2,516 Subsidiary dividends paid to non-controlling interests — (270 ) (270 ) Equity at June 30, 2017 $ 1,530,423 $ 21,390 $ 1,551,813 Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Defined Benefit Pension Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2017 $ 6,303 $ 16,216 $ 22,519 Other comprehensive income (loss) before reclassifications — 3,947 3,947 Amounts reclassified from accumulated other comprehensive income (loss) (81 ) — (81 ) Other comprehensive income (loss) (81 ) 3,947 3,866 Accumulated other comprehensive income (loss) at June 30, 2018 $ 6,222 $ 20,163 $ 26,385 Defined Benefit Pension Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2016 $ 1,138 $ 5,124 $ 6,262 Other comprehensive income (loss) before reclassifications — 12,753 12,753 Amounts reclassified from accumulated other comprehensive income (loss) 248 — 248 Other comprehensive income (loss) 248 12,753 13,001 Accumulated other comprehensive income (loss) at June 30, 2017 $ 1,386 $ 17,877 $ 19,263 Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost ( Note 14 ).

Factoring of Accounts Receivabl

Factoring of Accounts Receivable	6 Months Ended
	Jun. 30, 2018
Factoring of Accounts Receivable [Abstract]
Factoring of Accounts Receivable	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 and six months ended June 30, 2018 , we sold accounts receivable totaling $203.1 million and $428.6 million , net of discounts and fees of $2.0 million and $3.8 million , respectively. For the three and six months ended June 30, 2017 , we sold accounts receivable totaling $133.1 million and $265.2 million , net of discounts and fees of $0.8 million and $1.5 million , respectively.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Property, Plant And Equipment	Property, Plant and Equipment Property, plant and equipment consist of the following: June 30, December 31, 2017 (In thousands) Land $ 225,493 $ 224,894 Land use rights 26,845 26,845 Buildings and improvements 1,496,683 1,384,846 Machinery and equipment 5,131,573 4,938,291 Software and computer equipment 206,219 200,500 Furniture, fixtures and other equipment 16,664 15,722 Construction in progress 57,334 104,910 Total property, plant and equipment 7,160,811 6,896,008 Accumulated depreciation and amortization (4,405,851 ) (4,200,943 ) Total property, plant and equipment, net $ 2,754,960 $ 2,695,065 The following table summarizes our depreciation expense: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Depreciation expense $ 142,497 $ 144,839 $ 284,502 $ 286,295 As part of our plan to consolidate factory operations in Korea, we sold the land and buildings comprising our K1 factory in May 2017 for $142.4 million . We received 10% of the sale price at signing in November 2016 and the balance at closing, at which time we recognized a pre-tax gain of $108.1 million .

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following: June 30, December 31, (In thousands) Payroll and benefits $ 113,990 $ 134,785 Income taxes payable 23,658 56,664 Accrued settlement costs 19,212 37,783 Deferred revenue and customer advances 16,724 14,740 Accrued severance plan obligations 14,937 15,190 Accrued interest 11,728 11,873 Other accrued expenses 54,099 59,833 Total accrued expenses $ 254,348 $ 330,868

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt Following is a summary of short-term borrowings and long-term debt: June 30, December 31, (In thousands) Debt of Amkor Technology, Inc.: Senior secured credit facilities: $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due $ — $ — Senior notes: 6.625% Senior notes, due June 2021 (2) 200,000 200,000 6.375% Senior notes, due October 2022 524,971 524,971 Debt of subsidiaries: Amkor Technology Korea, Inc.: $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2018 (3) 75,000 75,000 Term loan, LIBOR plus 2.70%, due December 2019 — 55,000 Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 141,000 150,000 Term loan, fixed rate at 3.70%, due May 2020 120,000 120,000 Term loan, fund floating rate plus 1.60%, due June 2020 (4) 150,000 86,000 J-Devices Corporation: Short-term term loans, variable rate (5) 7,223 30,455 Term loans, fixed rate at 0.53%, due April 2018 — 6,744 Term loan, fixed rate at 0.86%, due June 2022 36,114 39,933 Term loan, fixed rate at 0.60%, due July 2022 7,674 8,430 Other: Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) (6) 20,000 20,000 Term loan, LIBOR plus 1.80%, due December 2019 (China) 48,500 49,000 1,330,482 1,365,533 Less: Unamortized premium and deferred debt costs, net (890 ) (1,104 ) Less: Short-term borrowings and current portion of long-term debt (115,057 ) (123,848 ) Long-term debt $ 1,214,535 $ 1,240,581 (1) As of June 30, 2018 , we had availability of $199.5 million under a senior secured revolving credit facility, after reduction of $0.5 million of outstanding standby letters of credit. In July 2018, this credit facility was terminated and replaced by a new facility entered into by Amkor Technology Singapore Holding Pte, Ltd. and guaranteed by Amkor Technology, Inc. This new credit facility has availability up to $250.0 million , a letter of credit sub-limit facility of $15.0 million and a termination date of July 2023. The availability for this revolving credit facility is limited to a percentage of the amount of eligible accounts receivable. (2) In July 2018, we issued a redemption notice for all $200 million of our 6.625% Senior Notes due 2021 ("Notes"). The note redemption is scheduled for completion in August 2018. In accordance with the terms of the indenture governing the Notes, the redemption price will be 100% of the principal amount of the Notes plus accrued and unpaid interest. The redemption of the Notes will be funded with proceeds from our ¥26.0 billion (approximately US $230 million ) term loan agreement entered into in July 2018 by J-Devices Corporation and guaranteed by Amkor Technology, Inc. The term loan bears interest at a fixed rate of 1.30% per annum. Principal and interest of the term loan are payable quarterly through the maturity in July 2023. (3) In June 2018, we extended our $75.0 million credit facility from June 2018 to September 2018. Principal is payable at maturity. Interest is due monthly in arrears, at a foreign currency funding-linked base rate plus 1.60% ( 4.66% as of June 30, 2018 ). (4) In May 2015, we entered into a term loan agreement pursuant to which we may borrow up to $150.0 million for capital expenditures. Principal is payable at maturity. Interest is payable quarterly in arrears, at a fund floating rate plus 1.60% ( 4.27% as of June 30, 2018 ). In the second quarter of 2018, we borrowed $64.0 million on this facility and repaid other Amkor Technology Korea, Inc. term loans with earlier maturity dates. (5) We entered into various short-term term loans which mature semiannually. Principal and interest is payable in monthly installments. Interest as of June 30, 2018 is at TIBOR plus 0.15% . As of June 30, 2018 , $9.0 million was available to be drawn. (6) In November 2015, we entered into a $39.0 million revolving credit facility. Principal is payable at maturity. Interest is payable monthly, at TAIFX plus a bank determined spread ( 3.75% as of June 30, 2018 ). As of June 30, 2018 , $19.0 million was available to be drawn. Certain of our foreign debt is collateralized by the land, buildings and equipment in the respective locations. The carrying value of the collateral exceeds the carrying amount of the debt. 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. From time to time, Amkor Technology, Inc. also guarantees certain debt of our subsidiaries. The agreements governing our indebtedness contain 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 debt covenants at June 30, 2018 .

Pension Plans

Pension Plans	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Pension Plans	Pension Plans Foreign Defined Benefit Pension Plans Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit pension plans. Charges to expense are based upon actuarial analyses. The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Service cost $ 8,299 $ 8,430 $ 16,715 $ 16,770 Interest cost 1,226 1,013 2,469 2,020 Expected return on plan assets (1,417 ) (1,133 ) (2,859 ) (2,261 ) Amortization of prior service cost — — — 31 Recognized actuarial (gain) loss (42 ) 22 (77 ) 44 Net periodic pension cost $ 8,066 $ 8,332 $ 16,248 $ 16,604 The components of net periodic pension cost other than the service cost component are included in other (income) expense, net in our Consolidated Statements of Income. Defined Contribution Pension Plans We sponsor defined contribution pension plans in Korea, Malaysia, Taiwan and the U.S. The following table summarizes our defined contribution expense: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Defined contribution expense $ 3,017 $ 2,581 $ 7,013 $ 5,779

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 certain other non-current assets and 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. We also review goodwill for impairment annually during the fourth quarter of each year. 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. Recurring fair value measurements consist of the following: June 30, December 31, (In thousands) Cash equivalent money market funds (Level 1) $ 75,167 $ 121,627 Restricted cash money market funds (Level 1) 2,000 2,000 We also measure certain assets and liabilities, including property, plant and equipment and goodwill, 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: June 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 736,693 $ 724,081 $ 745,943 $ 723,867 Revolving credit facilities and term loans (Level 2) 603,645 605,511 639,689 640,562 Total debt $ 1,340,338 $ 1,329,592 $ 1,385,632 $ 1,364,429 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 facilities and term loans is calculated using a discounted cash flow analysis, which utilizes market-based assumptions including forward interest rates adjusted for credit risk.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies 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. Although the outcome of these matters is uncertain, 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. 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 we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Interim Financial Statements (P

Interim Financial Statements (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation. The Consolidated Financial Statements and related disclosures as of June 30, 2018 , and for the three and six months ended June 30, 2018 and 2017 , are unaudited, pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). The December 31, 2017 , 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, 2017 , filed on Form 10-K with the SEC on February 23, 2018. The results of operations for the three and six months ended June 30, 2018 , 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.
Accounting Standards Update, Recently Adopted Standards and Recently Issued Standards	Effective January 1, 2018, we adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606) , using the full retrospective transition method as discussed in Note 2 . All amounts and disclosures set forth in this Form 10-Q reflect these changes. Recently Adopted Standards In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606), which was subsequently amended and clarified. The standard 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. The standard permits the use of either full retrospective or modified retrospective methods of adoption. Effective January 1, 2018, we adopted the requirements of Topic 606 using the full retrospective transition method. The new standard resulted in a change to the timing of revenue recognition, whereby revenue is recognized "over time" as services are performed rather than at a "point in time", generally upon shipment. The new standard also resulted in an increase in accounts receivables, net and a related decrease in inventories and deferred revenues. In accordance with Topic 606, we applied the following principles in connection with the adoption of the new standard: • We do not disclose the value of unsatisfied performance obligations for contracts with an original expected length of one year or less. • We do not adjust the promised amount of consideration for the effects of a significant financing component when we expect, at contract inception, that the period between when the entity transfers a promised good or service to a customer and when the customer pays for that good or service will be one year or less. • We exclude sales, use, value-added and similar taxes from the transaction price, without performing a jurisdiction-by-jurisdiction assessment. The adoption of the standard impacted our previously reported results as follows: For the Three Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 989,447 $ 18,938 $ 1,008,385 Cost of sales 817,212 14,557 831,769 Gross profit 172,235 4,381 176,616 Income tax expense 32,573 893 33,466 Net income 116,459 3,571 120,030 Net income attributable to Amkor 115,507 3,506 119,013 Net income attributable to Amkor per common share - diluted 0.48 0.02 0.50 For the Six Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 1,903,047 $ 4,622 $ 1,907,669 Cost of sales 1,587,906 6,913 1,594,819 Gross profit 315,141 (2,291 ) 312,850 Income tax expense 33,012 (871 ) 32,141 Net income 107,315 (1,253 ) 106,062 Net income attributable to Amkor 105,501 (1,274 ) 104,227 Net income attributable to Amkor per common share - diluted 0.44 — 0.44 December 31, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands) Balance Sheet: Accounts receivable, net $ 692,287 $ 105,977 $ 798,264 Inventories 326,492 (112,843 ) 213,649 Other assets 146,051 (6,255 ) 139,796 Accrued expenses 374,598 (43,730 ) 330,868 Other non-current liabilities 46,144 1,679 47,823 Accumulated deficit (1) (42,851 ) 28,948 (13,903 ) (1) The adjustment to accumulated deficit includes the 2017 and 2016 net income impact for the adoption of Topic 606 of $2.8 million and $11.3 million , respectively. The adjustment also includes the cumulative impact to our 2016 beginning accumulated deficit of $14.8 million . The adoption of the standard had no impact on cash provided by or used in operating, investing, or financing activities on our consolidated cash flow statements. In March 2017, the FASB issued ASU 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . ASU 2017-07 requires that the service cost component of net periodic pension costs be presented in the same line item as other compensation costs and all other components of net periodic pension costs be presented in the statement of income as nonoperating expenses. ASU 2017-07 is effective for reporting periods beginning after December 15, 2017 and applied retrospectively. We adopted ASU 2017-07 on January 1, 2018 and estimated the impact on the prior comparative period information presented in the consolidated financial statements applying the principles permitted by the standard. For the three and six months ended June 30, 2017 , the retrospective application resulted in a $(0.1) million and $0.2 million reclassification of pension costs from operating income to other (income) expense, net in the Consolidated Statements of Income for the respective periods. Refer to Note 14 for additional information. Recently Issued Standards In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which was subsequently amended and clarified. ASU 2016-02 requires a dual approach for lease accounting under which a lessee would account for leases as finance leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the right-of-use asset, and for operating leases the lessee would recognize a straight-line lease expense. ASU 2016-02 is effective for reporting periods beginning after December 15, 2018 and requires either a modified retrospective transition approach with application in all comparative periods presented, or an alternative transition method, which permits a company to use its effective date as the date of initial application without restating comparative period financial statements. Early adoption is permitted. We are currently evaluating the impact that this guidance may have on our financial statements and disclosure, and have not yet selected a transition method.
Use of Estimates	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.
Goodwill	Goodwill. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation.
Revenue Recognition	Revenue Recognition . We recognize revenue, net of sales, use, value-added and other similar taxes, after the following: – A contract with a customer has been identified – All performance obligations within the customer contract have been identified – The transaction price attributable to the contract has been determined and allocated to each performance obligation, and – The performance obligations have been determined to be satisfied. Performance obligations are deemed to be satisfied when, or as, control of services has been transferred to the customer. Our packaging and test services are our performance obligations to our customers. Our packaging services include wafer bump, probe and assembly. We provide packaging and test services to our customers either individually or as part of a combined offering. In a combined offering, we account for the individual services separately if they are determined to be distinct. We determine a service to be distinct if it is separately identifiable from other services in the combined offering and if a customer can benefit from the unique service on its own or with other resources that are readily available to the customer. The consideration, including variable consideration, is allocated between the distinct services in a combined offering based upon the stand-alone selling prices of the individual services. Our services involve a high degree of specialization which are unique based on the design and purpose of the customer’s wafers. Accordingly, our negotiated pricing reflects the customized nature of our services and represents a customer-specific stand-alone selling price. We recognize revenue as services are rendered, which generally occurs over the course of two to three weeks. Services are generally billed at completion of each individual packaging or test service or in some instances at the completion of all services in a combined offering. We recognize revenue over time as services are rendered because our services create or enhance the customer’s wafer. We utilize an input method (cost incurred plus estimated margin) to determine the amount of revenue to recognize for in-process, but incomplete customer orders at a reporting date. During the period of providing our services, we generally do not control or take ownership of customers' wafers, nor do we include the cost of the wafer in our cost calculations. We believe that a cost-based input method is the most appropriate manner to measure how we satisfy our performance obligations to customers because the effort and costs incurred to package and/or test customer wafers are not linear over the duration of these services. Shipping and handling costs are accounted for as a cost to fulfill our performance obligations to customers. Accordingly, we record customer payments of shipping and handling costs as a component of net sales, and the costs incurred for shipping and handling are then charged to cost of sales.
Unbilled Receivables	Unbilled Receivables . Unbilled receivables are revenues that have been recognized for performance obligations that have been satisfied, or partially satisfied, in advance of billing the customer. Revenue may be recognized in advance of billing as our contracts provide us with an unconditional right to consideration for work that is performed. Total unbilled receivables as of June 30, 2018 and December 31, 2017 were $106.6 million and $101.9 million , respectively. These amounts are included in accounts receivable, net of allowances in our Consolidated Balance Sheets.
Inventories	Inventories. Inventories consist of raw materials and purchased components, and are stated at the lower of cost and net realizable value. Cost is principally determined by standard cost or the weighted moving average method, both of which approximate actual cost. We review and set our standard costs as needed, but at a minimum on an annual basis. We reduce the carrying value of our inventories for the cost of inventory we estimate is excess and obsolete based on the age of our inventories. When a determination is made that the inventory will not be utilized in production or is not saleable, it is written-off.
Income Taxes	We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and results of recent operations. Except for deferred tax assets in Portugal, we consider it more likely than not that we will have sufficient taxable income to allow us to realize most of our foreign deferred tax assets. We maintain a valuation allowance on a portion of our U.S. net deferred tax assets, for net operating loss carryforwards not expected to be realized due to Global Intangible Low-Taxed Income ("GILTI") and foreign tax credit carryforwards expected to expire unused. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized.
Commitments and Contingencies	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. 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 we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

New Accounting Standards (Table

New Accounting Standards (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of the impacted previously reported results	The adoption of the standard impacted our previously reported results as follows: For the Three Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 989,447 $ 18,938 $ 1,008,385 Cost of sales 817,212 14,557 831,769 Gross profit 172,235 4,381 176,616 Income tax expense 32,573 893 33,466 Net income 116,459 3,571 120,030 Net income attributable to Amkor 115,507 3,506 119,013 Net income attributable to Amkor per common share - diluted 0.48 0.02 0.50 For the Six Months Ended June 30, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands, except per share data) Income Statement: Net sales $ 1,903,047 $ 4,622 $ 1,907,669 Cost of sales 1,587,906 6,913 1,594,819 Gross profit 315,141 (2,291 ) 312,850 Income tax expense 33,012 (871 ) 32,141 Net income 107,315 (1,253 ) 106,062 Net income attributable to Amkor 105,501 (1,274 ) 104,227 Net income attributable to Amkor per common share - diluted 0.44 — 0.44 December 31, 2017 As Previously Reported New Accounting Pronouncement Adjustment As Adjusted (In thousands) Balance Sheet: Accounts receivable, net $ 692,287 $ 105,977 $ 798,264 Inventories 326,492 (112,843 ) 213,649 Other assets 146,051 (6,255 ) 139,796 Accrued expenses 374,598 (43,730 ) 330,868 Other non-current liabilities 46,144 1,679 47,823 Accumulated deficit (1) (42,851 ) 28,948 (13,903 ) (1) The adjustment to accumulated deficit includes the 2017 and 2016 net income impact for the adoption of Topic 606 of $2.8 million and $11.3 million , respectively. The adjustment also includes the cumulative impact to our 2016 beginning accumulated deficit of $14.8 million .

Net Sales by Product Group an25

Net Sales by Product Group and End Market (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Net sales by product group and end market	The following table presents net sales by end market : For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 Communications (smartphones, tablets, handheld devices) 42 % 40 % 42 % 39 % Automotive, industrial and other (driver assist, infotainment, safety, performance) 26 % 27 % 26 % 28 % Computing (datacenter, infrastructure, PC/laptop, storage) 19 % 19 % 19 % 19 % Consumer (set-top boxes, televisions, connected home, personal electronics, visual imaging) 13 % 14 % 13 % 14 % Total net sales 100 % 100 % 100 % 100 % The following table presents net sales by product group: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) (In thousands) Advanced products (1) $ 496,241 $ 445,100 $ 971,993 $ 820,967 Mainstream products (2) 569,443 563,285 1,119,010 1,086,702 Total net sales $ 1,065,684 $ 1,008,385 $ 2,091,003 $ 1,907,669 (1) Advanced products include flip chip and wafer-level processing and related test services (2) Mainstream products include wirebond packaging and related test services

Other Income and Expense (Table

Other Income and Expense (Tables)	6 Months Ended
	Jun. 30, 2018
Other Income and Expenses [Abstract]
Schedule of other income and expense	Other income and expense consists of the following: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Interest income $ (955 ) $ (955 ) $ (1,943 ) $ (1,466 ) Foreign currency (gain) loss, net (7,110 ) (2,252 ) (2,397 ) 9,132 Other (2,936 ) (81 ) (3,229 ) 227 Other (income) expense, net $ (11,001 ) $ (3,288 ) $ (7,569 ) $ 7,893

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
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 June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands, except per share data) Net income attributable to Amkor common stockholders $ 32,591 $ 119,013 $ 42,135 $ 104,227 Weighted-average number of common shares outstanding — basic 239,351 238,863 239,283 238,774 Effect of dilutive securities: Stock options and restricted share awards 453 816 522 827 Weighted-average number of common shares outstanding — diluted 239,804 239,679 239,805 239,601 Net income attributable to Amkor per common share: Basic $ 0.14 $ 0.50 $ 0.18 $ 0.44 Diluted 0.14 0.50 0.18 0.44
Summary of potential shares of common stock 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 anti-dilutive: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Stock options and restricted share awards 3,644 3,193 3,524 3,473

Equity and Accumulated Other 28

Equity and Accumulated Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Changes in equity	Changes in equity consist of the following: Attributable to Amkor Attributable to Non-controlling Interests Total (In thousands) Equity at December 31, 2017 $ 1,696,276 $ 23,433 $ 1,719,709 Net income 42,135 1,244 43,379 Other comprehensive income (loss) 3,866 — 3,866 Issuance of stock through employee share-based compensation plans 1,023 — 1,023 Treasury stock acquired through surrender of shares for tax withholding (105 ) — (105 ) Share-based compensation 2,556 — 2,556 Subsidiary dividends paid to non-controlling interests — (270 ) (270 ) Equity at June 30, 2018 $ 1,745,751 $ 24,407 $ 1,770,158 Attributable to Amkor Attributable to Non-controlling Interests Total (In thousands) Equity at December 31, 2016 $ 1,409,692 $ 19,825 $ 1,429,517 Net income 104,227 1,835 106,062 Other comprehensive income (loss) 13,001 — 13,001 Issuance of stock through employee share-based compensation plans 2,365 — 2,365 Treasury stock acquired through surrender of shares for tax withholding (1,378 ) — (1,378 ) Share-based compensation 2,516 — 2,516 Subsidiary dividends paid to non-controlling interests — (270 ) (270 ) Equity at June 30, 2017 $ 1,530,423 $ 21,390 $ 1,551,813
Changes in accumulated other comprehensive income (loss), net of tax	Changes in accumulated other comprehensive income (loss), net of tax, consist of the following: Defined Benefit Pension Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2017 $ 6,303 $ 16,216 $ 22,519 Other comprehensive income (loss) before reclassifications — 3,947 3,947 Amounts reclassified from accumulated other comprehensive income (loss) (81 ) — (81 ) Other comprehensive income (loss) (81 ) 3,947 3,866 Accumulated other comprehensive income (loss) at June 30, 2018 $ 6,222 $ 20,163 $ 26,385 Defined Benefit Pension Foreign Currency Translation Total (In thousands) Accumulated other comprehensive income (loss) at December 31, 2016 $ 1,138 $ 5,124 $ 6,262 Other comprehensive income (loss) before reclassifications — 12,753 12,753 Amounts reclassified from accumulated other comprehensive income (loss) 248 — 248 Other comprehensive income (loss) 248 12,753 13,001 Accumulated other comprehensive income (loss) at June 30, 2017 $ 1,386 $ 17,877 $ 19,263

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Summary of property, plant and equipment and depreciation expense	Property, plant and equipment consist of the following: June 30, December 31, 2017 (In thousands) Land $ 225,493 $ 224,894 Land use rights 26,845 26,845 Buildings and improvements 1,496,683 1,384,846 Machinery and equipment 5,131,573 4,938,291 Software and computer equipment 206,219 200,500 Furniture, fixtures and other equipment 16,664 15,722 Construction in progress 57,334 104,910 Total property, plant and equipment 7,160,811 6,896,008 Accumulated depreciation and amortization (4,405,851 ) (4,200,943 ) Total property, plant and equipment, net $ 2,754,960 $ 2,695,065 The following table summarizes our depreciation expense: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Depreciation expense $ 142,497 $ 144,839 $ 284,502 $ 286,295

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2018
Payables and Accruals [Abstract]
Summary of accrued expenses	Accrued expenses consist of the following: June 30, December 31, (In thousands) Payroll and benefits $ 113,990 $ 134,785 Income taxes payable 23,658 56,664 Accrued settlement costs 19,212 37,783 Deferred revenue and customer advances 16,724 14,740 Accrued severance plan obligations 14,937 15,190 Accrued interest 11,728 11,873 Other accrued expenses 54,099 59,833 Total accrued expenses $ 254,348 $ 330,868

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Summary of short-term borrowings and long-term debt	Following is a summary of short-term borrowings and long-term debt: June 30, December 31, (In thousands) Debt of Amkor Technology, Inc.: Senior secured credit facilities: $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due $ — $ — Senior notes: 6.625% Senior notes, due June 2021 (2) 200,000 200,000 6.375% Senior notes, due October 2022 524,971 524,971 Debt of subsidiaries: Amkor Technology Korea, Inc.: $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2018 (3) 75,000 75,000 Term loan, LIBOR plus 2.70%, due December 2019 — 55,000 Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 141,000 150,000 Term loan, fixed rate at 3.70%, due May 2020 120,000 120,000 Term loan, fund floating rate plus 1.60%, due June 2020 (4) 150,000 86,000 J-Devices Corporation: Short-term term loans, variable rate (5) 7,223 30,455 Term loans, fixed rate at 0.53%, due April 2018 — 6,744 Term loan, fixed rate at 0.86%, due June 2022 36,114 39,933 Term loan, fixed rate at 0.60%, due July 2022 7,674 8,430 Other: Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) (6) 20,000 20,000 Term loan, LIBOR plus 1.80%, due December 2019 (China) 48,500 49,000 1,330,482 1,365,533 Less: Unamortized premium and deferred debt costs, net (890 ) (1,104 ) Less: Short-term borrowings and current portion of long-term debt (115,057 ) (123,848 ) Long-term debt $ 1,214,535 $ 1,240,581 (1) As of June 30, 2018 , we had availability of $199.5 million under a senior secured revolving credit facility, after reduction of $0.5 million of outstanding standby letters of credit. In July 2018, this credit facility was terminated and replaced by a new facility entered into by Amkor Technology Singapore Holding Pte, Ltd. and guaranteed by Amkor Technology, Inc. This new credit facility has availability up to $250.0 million , a letter of credit sub-limit facility of $15.0 million and a termination date of July 2023. The availability for this revolving credit facility is limited to a percentage of the amount of eligible accounts receivable. (2) In July 2018, we issued a redemption notice for all $200 million of our 6.625% Senior Notes due 2021 ("Notes"). The note redemption is scheduled for completion in August 2018. In accordance with the terms of the indenture governing the Notes, the redemption price will be 100% of the principal amount of the Notes plus accrued and unpaid interest. The redemption of the Notes will be funded with proceeds from our ¥26.0 billion (approximately US $230 million ) term loan agreement entered into in July 2018 by J-Devices Corporation and guaranteed by Amkor Technology, Inc. The term loan bears interest at a fixed rate of 1.30% per annum. Principal and interest of the term loan are payable quarterly through the maturity in July 2023. (3) In June 2018, we extended our $75.0 million credit facility from June 2018 to September 2018. Principal is payable at maturity. Interest is due monthly in arrears, at a foreign currency funding-linked base rate plus 1.60% ( 4.66% as of June 30, 2018 ). (4) In May 2015, we entered into a term loan agreement pursuant to which we may borrow up to $150.0 million for capital expenditures. Principal is payable at maturity. Interest is payable quarterly in arrears, at a fund floating rate plus 1.60% ( 4.27% as of June 30, 2018 ). In the second quarter of 2018, we borrowed $64.0 million on this facility and repaid other Amkor Technology Korea, Inc. term loans with earlier maturity dates. (5) We entered into various short-term term loans which mature semiannually. Principal and interest is payable in monthly installments. Interest as of June 30, 2018 is at TIBOR plus 0.15% . As of June 30, 2018 , $9.0 million was available to be drawn. (6) In November 2015, we entered into a $39.0 million revolving credit facility. Principal is payable at maturity. Interest is payable monthly, at TAIFX plus a bank determined spread ( 3.75% as of June 30, 2018 ). As of June 30, 2018 , $19.0 million was available to be drawn.

Pension Plans (Tables)

Pension Plans (Tables)	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Components of net periodic pension cost	The components of net periodic pension cost for these defined benefit pension plans are as follows: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Service cost $ 8,299 $ 8,430 $ 16,715 $ 16,770 Interest cost 1,226 1,013 2,469 2,020 Expected return on plan assets (1,417 ) (1,133 ) (2,859 ) (2,261 ) Amortization of prior service cost — — — 31 Recognized actuarial (gain) loss (42 ) 22 (77 ) 44 Net periodic pension cost $ 8,066 $ 8,332 $ 16,248 $ 16,604
Summary of defined contribution expense	The following table summarizes our defined contribution expense: For the Three Months Ended June 30, For the Six Months Ended June 30, 2018 2017 2018 2017 (In thousands) Defined contribution expense $ 3,017 $ 2,581 $ 7,013 $ 5,779

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Recurring fair value measurements	Recurring fair value measurements consist of the following: June 30, December 31, (In thousands) Cash equivalent money market funds (Level 1) $ 75,167 $ 121,627 Restricted cash money market funds (Level 1) 2,000 2,000
Fair value of financial instruments that are not recorded at fair value on recurring basis	The following table presents the fair value of financial instruments that are not recorded at fair value on a recurring basis: June 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value (In thousands) Senior notes (Level 1) $ 736,693 $ 724,081 $ 745,943 $ 723,867 Revolving credit facilities and term loans (Level 2) 603,645 605,511 639,689 640,562 Total debt $ 1,340,338 $ 1,329,592 $ 1,385,632 $ 1,364,429

New Accounting Standards - Reve

New Accounting Standards - Revenue from Contracts with Customers (Topic 606) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales	$ 1,065,684	$ 1,008,385	$ 2,091,003	$ 1,907,669
Cost of sales	895,967	831,769	1,763,515	1,594,819
Gross profit	169,717	176,616	327,488	312,850
Income tax expense	10,631	33,466	13,112	32,141
Net income	33,184	120,030	43,379	106,062
Net income attributable to Amkor	$ 32,591	$ 119,013	$ 42,135	$ 104,227
Net loss attributable to Amkor per common share - diluted (in dollars per share)	$ 0.14	$ 0.50	$ 0.18	$ 0.44
Accounts receivable, net	$ 795,750		$ 795,750		$ 798,264
Inventories	243,019		243,019		213,649
Other assets	139,567		139,567		139,796
Accrued expenses	254,348		254,348		330,868
Other non-current liabilities	51,264		51,264		47,823
Accumulated deficit	$ 28,232		$ 28,232		(13,903)
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales		$ 989,447		$ 1,903,047
Cost of sales		817,212		1,587,906
Gross profit		172,235		315,141
Income tax expense		32,573		33,012
Net income		116,459		107,315
Net income attributable to Amkor		$ 115,507		$ 105,501
Net loss attributable to Amkor per common share - diluted (in dollars per share)		$ 0.48		$ 0.44
Accounts receivable, net					692,287
Inventories					326,492
Other assets					146,051
Accrued expenses					374,598
Other non-current liabilities					46,144
Accumulated deficit					(42,851)
New Accounting Pronouncement Adjustment | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net sales		$ 18,938		$ 4,622
Cost of sales		14,557		6,913
Gross profit		4,381		(2,291)
Income tax expense		893		(871)
Net income		3,571		(1,253)
Net income attributable to Amkor		$ 3,506		$ (1,274)
Net loss attributable to Amkor per common share - diluted (in dollars per share)		$ 0.02		$ 0
Accounts receivable, net					105,977
Inventories					(112,843)
Other assets					(6,255)
Accrued expenses					(43,730)
Other non-current liabilities					1,679
Accumulated deficit					28,948
New Accounting Pronouncement Adjustment | ASU 2014-09 | Adjustment to Accumulated Deficit
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Adjustment to accumulated deficit					$ 2,800	$ 11,300	$ 14,800

New Accounting Standards - Comp

New Accounting Standards - Compensation – Retirement Benefits (Topic 715) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income	$ (53,941)	$ (172,659)	$ (90,060)	$ (191,043)
Other (income) expense, net	$ 11,001	3,288	$ 7,569	(7,893)
ASU 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating income		(100)		200
Other (income) expense, net		$ 100		$ (200)

Significant Accounting Polici36

Significant Accounting Policies (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Unbilled receivables	$ 106.6	$ 101.9
Minimum
Disaggregation of Revenue [Line Items]
Course of recognition	14 days
Maximum
Disaggregation of Revenue [Line Items]
Course of recognition	21 days

Acquisition (Details)

Acquisition (Details)	May 22, 2017
Nanium S.A.
Business Acquisition [Line Items]
Ownership interest acquired (as a percent)	100.00%

Net Sales by Product Group an38

Net Sales by Product Group and End Market - Net Sales by Product Group (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Net sales by product group	$ 1,065,684	$ 1,008,385	$ 2,091,003	$ 1,907,669
Advanced products
Disaggregation of Revenue [Line Items]
Net sales by product group	496,241	445,100	971,993	820,967
Mainstream products
Disaggregation of Revenue [Line Items]
Net sales by product group	$ 569,443	$ 563,285	$ 1,119,010	$ 1,086,702

Net Sales by Product Group an39

Net Sales by Product Group and End Market - Net Sales by End Market (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total net sales	100.00%	100.00%
Revenue from Contract with Customer | End Market | Communications (smartphones, tablets, handheld devices)
Disaggregation of Revenue [Line Items]
Total net sales	42.00%	40.00%	42.00%	39.00%
Revenue from Contract with Customer | End Market | Automotive, industrial and other (driver assist, infotainment, safety, performance)
Disaggregation of Revenue [Line Items]
Total net sales	26.00%	27.00%	26.00%	28.00%
Revenue from Contract with Customer | End Market | Computing (datacenter, infrastructure, PC/laptop, storage)
Disaggregation of Revenue [Line Items]
Total net sales	19.00%	19.00%	19.00%	19.00%
Revenue from Contract with Customer | End Market | Consumer (set-top boxes, televisions, connected home, personal electronics, visual imaging)
Disaggregation of Revenue [Line Items]
Total net sales	13.00%	14.00%	13.00%	14.00%

Other Income and Expense (Detai

Other Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Income and Expenses [Abstract]
Interest income	$ (955)	$ (955)	$ (1,943)	$ (1,466)
Foreign currency (gain) loss, net	(7,110)	(2,252)	(2,397)	9,132
Other	(2,936)	(81)	(3,229)	227
Other (income) expense, net	$ (11,001)	$ (3,288)	$ (7,569)	$ 7,893

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 10,631	$ 33,466	$ 13,112	$ 32,141
Gross unrecognized tax benefits	$ 24,800		$ 24,800		$ 27,200

Earnings Per Share - Computatio

Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income attributable to Amkor common stockholders	$ 32,591	$ 119,013	$ 42,135	$ 104,227
Weighted-average number of common shares outstanding — basic	239,351	238,863	239,283	238,774
Effect of dilutive securities:
Stock options and restricted share awards (in shares)	453	816	522	827
Weighted-average number of common shares outstanding — diluted	239,804	239,679	239,805	239,601
Net income attributable to Amkor per common share:
Basic (in dollars per share)	$ 0.14	$ 0.50	$ 0.18	$ 0.44
Diluted (in dollars per share)	$ 0.14	$ 0.50	$ 0.18	$ 0.44

Earnings Per Share - Summary of

Earnings Per Share - Summary of Potential Shares of Common Stock Excluded from Diluted EPS (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock options and restricted share awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options and restricted share awards	3,644	3,193	3,524	3,473

Equity and Accumulated Other 44

Equity and Accumulated Other Comprehensive Income (Loss) - Changes in Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 1,719,709	$ 1,429,517
Net income	$ 33,184	$ 120,030	43,379	106,062
Other comprehensive income (loss)	(11,186)	(815)	3,866	13,001
Issuance of stock through employee share-based compensation plans			1,023	2,365
Treasury stock acquired through surrender of shares for tax withholding			(105)	(1,378)
Share-based compensation			2,556	2,516
Subsidiary dividends paid to non-controlling interests			(270)	(270)
Ending balance	1,770,158	1,551,813	1,770,158	1,551,813
Attributable to Amkor
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			1,696,276	1,409,692
Net income			42,135	104,227
Other comprehensive income (loss)			3,866	13,001
Issuance of stock through employee share-based compensation plans			1,023	2,365
Treasury stock acquired through surrender of shares for tax withholding			(105)	(1,378)
Share-based compensation			2,556	2,516
Subsidiary dividends paid to non-controlling interests			0	0
Ending balance	1,745,751	1,530,423	1,745,751	1,530,423
Attributable to Non-controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			23,433	19,825
Net income			1,244	1,835
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			0	0
Subsidiary dividends paid to non-controlling interests			(270)	(270)
Ending balance	$ 24,407	$ 21,390	$ 24,407	$ 21,390

Equity and Accumulated Other 45

Equity and Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ 1,719,709	$ 1,429,517
Other comprehensive income (loss) before reclassifications			3,947	12,753
Amounts reclassified from accumulated other comprehensive income (loss)			(81)	248
Total other comprehensive income (loss)	$ (11,186)	$ (815)	3,866	13,001
Ending balance	1,770,158	1,551,813	1,770,158	1,551,813
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			6,303	1,138
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income (loss)			(81)	248
Total other comprehensive income (loss)			(81)	248
Ending balance	6,222	1,386	6,222	1,386
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			16,216	5,124
Other comprehensive income (loss) before reclassifications			3,947	12,753
Amounts reclassified from accumulated other comprehensive income (loss)			0	0
Total other comprehensive income (loss)			3,947	12,753
Ending balance	20,163	17,877	20,163	17,877
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			22,519	6,262
Ending balance	$ 26,385	$ 19,263	$ 26,385	$ 19,263

Factoring of Accounts Receiva46

Factoring of Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total Factored
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 203.1	$ 133.1	$ 428.6	$ 265.2
Discounts and Fees
Factoring of Accounts Receivable [Line Items]
Accounts receivable sold	$ 2	$ 0.8	$ 3.8	$ 1.5

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 7,160,811	$ 6,896,008
Accumulated depreciation and amortization	(4,405,851)	(4,200,943)
Total property, plant and equipment, net	2,754,960	2,695,065
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	225,493	224,894
Land use rights
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	26,845	26,845
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	1,496,683	1,384,846
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	5,131,573	4,938,291
Software and computer equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	206,219	200,500
Furniture, fixtures and other equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	16,664	15,722
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 57,334	$ 104,910

Property, Plant and Equipment48

Property, Plant and Equipment - Summary of Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 142,497	$ 144,839	$ 284,502	$ 286,295

Property, Plant and Equipment49

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	May 31, 2017	Nov. 30, 2016	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Proceeds from sale of property, plant and equipment					$ 603	$ 130,962
Pre-tax gain at close			$ 0	$ 108,109	$ 0	$ 108,109
Korea
Property, Plant and Equipment [Line Items]
Proceeds from sale of property, plant and equipment	$ 142,400
Percentage of proceeds received		10.00%
Pre-tax gain at close	$ 108,100

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Payroll and benefits	$ 113,990	$ 134,785
Income taxes payable	23,658	56,664
Accrued settlement costs	19,212	37,783
Deferred revenue and customer advances	16,724	14,740
Accrued severance plan obligations	14,937	15,190
Accrued interest	11,728	11,873
Other accrued expenses	54,099	59,833
Total accrued expenses	$ 254,348	$ 330,868

Debt (Details)

Debt (Details) ¥ in Billions	1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 31, 2018JPY (¥)	Jun. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jul. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Nov. 30, 2015USD ($)	May 31, 2015USD ($)
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 1,330,482,000	$ 1,330,482,000			$ 1,365,533,000
Less: Unamortized premium and deferred debt costs, net		(890,000)	(890,000)			(1,104,000)
Less: Short-term borrowings and current portion of long-term debt		(115,057,000)	(115,057,000)			(123,848,000)
Long-term debt		1,214,535,000	1,214,535,000			1,240,581,000
Proceeds from revolving credit facilities			0	$ 75,000,000
Letter of Credit
Debt Instrument [Line Items]
Standby letters of credit outstanding		500,000	500,000
Term loan, LIBOR plus 1.80%, due December 2019 (China) | China
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		48,500,000	$ 48,500,000			49,000,000
Term loan, LIBOR plus 1.80%, due December 2019 (China) | China | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.80%
Line of Credit | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Revolving Credit Facility
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		0	$ 0			0
Credit facility, borrowing capacity		200,000,000	200,000,000
Remaining borrowing capacity		199,500,000	$ 199,500,000
Line of Credit | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.25%
Line of Credit | $200 million revolving credit facility, LIBOR plus 1.25%-1.75%, due December 2019 | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.75%
Line of Credit | $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2019 | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			1.60%
Credit facility, borrowing capacity		$ 75,000,000	$ 75,000,000
Interest rate at period end (as a percent)		4.66%	4.66%
Line of Credit | $75 million revolving credit facility, foreign currency funding-linked base rate plus 1.60%, due September 2019 | Korea | Revolving Credit Facility
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 75,000,000	$ 75,000,000			75,000,000
Basis spread on variable rate (as a percent)			1.60%
Credit facility, borrowing capacity		75,000,000	$ 75,000,000
Line of Credit | Revolving credit facility, TAIFX plus a bank-determined spread, due November 2020 (Taiwan) | Taiwan | Revolving Credit Facility
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		20,000,000	20,000,000			20,000,000
Credit facility, borrowing capacity							$ 39,000,000
Remaining borrowing capacity		$ 19,000,000	$ 19,000,000
Interest rate at period end (as a percent)		3.75%	3.75%
Line of Credit | Senior secured revolving credit facility due July 2023 | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Credit facility, borrowing capacity					$ 250,000,000
Line of Credit | Senior secured revolving credit facility due July 2023 | Letter of Credit | Subsequent Event
Debt Instrument [Line Items]
Credit facility, borrowing capacity					$ 15,000,000
Senior Notes | 6.625% Senior notes, due June 2021 (2)
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 200,000,000	$ 200,000,000			200,000,000
Stated interest rate (as a percent)		6.625%	6.625%
Face amount of debt		$ 200,000,000	$ 200,000,000
Senior Notes | 6.625% Senior notes, due June 2021 (2) | Subsequent Event
Debt Instrument [Line Items]
Debt redemption price	100.00%
Senior Notes | 6.375% Senior notes, due October 2022
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 524,971,000	$ 524,971,000			524,971,000
Stated interest rate (as a percent)		6.375%	6.375%
Subsidiary Term Loans | Term loan, LIBOR plus 2.70%, due December 2019 | Korea
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 0	$ 0			55,000,000
Basis spread on variable rate (as a percent)			2.70%
Subsidiary Term Loans | Term loan, foreign currency funding-linked base rate plus 1.32%, due May 2020 | Korea
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		141,000,000	$ 141,000,000			150,000,000
Basis spread on variable rate (as a percent)			1.32%
Subsidiary Term Loans | Term loan, fund floating rate plus 1.60%, due June 2020 | Korea
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 150,000,000	$ 150,000,000			86,000,000
Basis spread on variable rate (as a percent)			1.60%
Credit facility, borrowing capacity								$ 150,000,000
Interest rate at period end (as a percent)		4.27%	4.27%
Proceeds from revolving credit facilities		$ 64,000,000
Subsidiary Term Loans | Short-term term loans, variable rate | Japan
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		7,223,000	$ 7,223,000			30,455,000
Remaining borrowing capacity		9,000,000	$ 9,000,000
Subsidiary Term Loans | Short-term term loans, variable rate | Japan | TIBOR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)			0.15%
Subsidiary Term Loans | Term loans, fixed rate at 0.53%, due April 2018 | Japan
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 0	$ 0			6,744,000
Stated interest rate (as a percent)		0.53%	0.53%
Subsidiary Term Loans | Term loan, fixed rate at 0.86%, due June 2022 | Japan
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 36,114,000	$ 36,114,000			39,933,000
Stated interest rate (as a percent)		0.86%	0.86%
Subsidiary Term Loans | Term loan, fixed rate at 0.60%, due July 2022 | Japan
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 7,674,000	$ 7,674,000			8,430,000
Stated interest rate (as a percent)		0.60%	0.60%
Term Loan | Term loan, fixed rate at 3.70%, due May 2020 | Korea
Debt Instrument [Line Items]
Short-term borrowings and long-term debt		$ 120,000,000	$ 120,000,000			$ 120,000,000
Stated interest rate (as a percent)		3.70%	3.70%
Term Loan | Term loan, fixed at 1.30% due July 2023 | Subsequent Event
Debt Instrument [Line Items]
Stated interest rate (as a percent)	1.297%				1.297%
Face amount of debt	¥ 26				$ 200,000,000

Pension Plans - Components of N

Pension Plans - Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Retirement Benefits [Abstract]
Service cost	$ 8,299	$ 8,430	$ 16,715	$ 16,770
Interest cost	1,226	1,013	2,469	2,020
Expected return on plan assets	(1,417)	(1,133)	(2,859)	(2,261)
Amortization of prior service cost	0	0	0	31
Recognized actuarial (gain) loss	(42)	22	(77)	44
Net periodic pension cost	$ 8,066	$ 8,332	$ 16,248	$ 16,604

Pension Plans - Summary of Defi

Pension Plans - Summary of Defined Contribution Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Retirement Benefits [Abstract]
Defined contribution expense	$ 3,017	$ 2,581	$ 7,013	$ 5,779

Fair Value Measurements - Recur

Fair Value Measurements - Recurring Fair Value Measurements (Details) - Recurring Fair Value Measurements - Level 1 - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalent money market funds	$ 75,167	$ 121,627
Restricted cash money market funds	$ 2,000	$ 2,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Instruments Not Recorded at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 1,340,338	$ 1,385,632
Fair Value | Senior notes | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	736,693	745,943
Fair Value | Revolving credit facilities and term loans | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	603,645	639,689
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	1,329,592	1,364,429
Carrying Value | Senior notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	724,081	723,867
Carrying Value | Revolving credit facilities and term loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 605,511	$ 640,562