Commitments and Contingencies	3 Months Ended
Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	16. Commitments and Contingencies We have a letter of credit sub-facility of $25.0 million under our $150.0 million senior secured revolving credit facility that matures in June 2017. As of March 31, 2014, we had $0.4 million of standby letters of credit outstanding and had an additional $24.6 million available for letters of credit. Such standby letters of credit are used in the ordinary course of our business and are collateralized by our cash balances. We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers' specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial. Legal Proceedings We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to make a determination as to the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. Except as indicated below, we believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future. In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred. Proceedings with Tessera, Inc. Since March 2006, we have been involved in several proceedings with Tessera Technologies, Inc. (“Tessera”) related to a license agreement (the “License Agreement”) entered into in 1996 between Tessera and our predecessor. The proceedings generally involve disputes about whether or not Amkor owes Tessera royalties under the License Agreement with respect to certain packages and the termination of the License Agreement. The main proceeding that is pending is with the International Court of Arbitration of the International Chamber of Commerce (the “ICC”) captioned Amkor Technology, Inc. v. Tessera, Inc. (the “2009 Arbitration”), which we initiated in August 2009. In that proceeding, the ICC arbitration panel has previously ruled that royalties are due to Tessera with respect to certain asserted patents and packages and that the License Agreement was terminated by Tessera as of February 17, 2011. The arbitration panel reserved for later decision the issues of the amount of royalties and pre-judgment interest due, and the allocation of costs. The other pending arbitration proceedings with Tessera include a request for arbitration by Tessera filed in May 2011 seeking undisclosed damages and a declaration that the License Agreement had been terminated, and a continuation of the 2009 proceeding related to three additional U.S. patents. In July 2012, Tessera filed a complaint in the U.S. District Court for the District of Delaware. The complaint seeks injunctive relief and damages with respect to Amkor's alleged infringement of one of the U.S. patents (U.S. Patent No. 6,046,076, the "'076 patent") that the arbitration panel found to be royalty bearing in the 2009 Arbitration. In November 2013, the parties agreed to stay the Delaware litigation. In February 2013, we filed a petition in the Superior Court for San Francisco County to vacate or correct a portion of the arbitration panel’s interim order relating to the panel’s authority to award royalties for the period after the termination of the License Agreement. The Superior Court has denied our request and we have appealed that decision to the California First District Court of Appeal. In April 2013, we initiated an inter partes review (the “IPR”) proceeding with the Patent Trial and Appeal Board at the United States Patent and Trademark Office (“U.S. PTO”), requesting it to find certain claims of the ‘076 patent unpatentable, including the two claims we were found to practice during the 2009 Arbitration. In October 2013, the U.S. PTO determined that there is a reasonable likelihood that we will prevail in challenging those claims and certain others. Tessera has challenged the IPR proceeding and is expected to continue with such efforts. The IPR is scheduled to go forward on the merits with a hearing in May 2014. In October 2013, January 2014 and March 2014, the arbitration panel issued additional interim orders which included, among other things, some substantive findings concerning the calculation of royalties under the License Agreement. In February 2014, Tessera filed a motion with the arbitration panel to enjoin us from proceeding with the IPR. We filed a response with the arbitration panel requesting it to deny Tessera's motion and to stay a portion of the 2009 Arbitration pending final resolution of the IPR proceeding. The arbitration panel denied both Tessera's motion and our request for a stay in March 2014. We expect the arbitration panel to award Tessera royalties of $113 million plus interest. Most of the royalties claimed by Tessera relate to Amkor's alleged use of the ‘076 patent and the period following termination of the License Agreement. Any award by the arbitration panel must be confirmed by the courts before Tessera can enforce the award against Amkor, and we believe that a favorable outcome in the IPR or in the other pending proceedings may materially and adversely impact Tessera’s ability to confirm and collect on any final award by the arbitration panel and other claims for damages. As a result of recent developments, the potential impact of the IPR proceeding on any award by the arbitration panel, and our position regarding potential royalties due to Tessera following the termination of the License Agreement, we reduced our estimate of the possible range of royalties due to Tessera in the 2009 Arbitration to be from $11 million to $113 million (net of royalties previously paid in 2012 and excluding interest). Our accrual for these royalties was $43.3 million at December 31, 2013. Although we have reduced our estimate of the low end of the range of possible royalties due, we have made a determination not to reduce our accrual due to the inherent uncertainty of the outcome in the various proceedings. The ultimate amount of damages and interest we may owe to Tessera in connection with the several pending proceedings could be more or less than our estimate of the possible range of royalties due in the 2009 Arbitration, and could be more or less than the amount we expect the arbitration panel to award. The final outcome of our litigation with Tessera depends upon a number of complex factors, including whether we receive a favorable ruling in the above proceedings and other factors. We may adjust our accrual as information develops or upon the issuance of new rulings. As of March 31, 2014, we have $4.9 million accrued for interest related to these royalties, and we expect to record our estimate of interest accruing with the passage of time. We strongly dispute Tessera's claims in these proceedings and intend to vigorously defend against them. However, the final outcome of these matters is uncertain, and an adverse result could have a material adverse effect on our results of operations, financial condition and cash flows. Amkor Technology, Inc. v. Carsem (M) Sdn Bhd, Carsem Semiconductor Sdn Bhd, and Carsem Inc. Since November 2003, we have been involved in several proceedings against Carsem (M) Sdn Bhd, Carsem Semiconductor Sdn Bhd, and Carsem Inc. (collectively “Carsem”) in which we allege that with its Carsem Dual and Quad Flat No-Lead Packages, Carsem has infringed on one or more of our MicroLeadFrame packaging technology patent claims. We initiated the action with the U.S International Trade Commission (the “ITC”) in Washington, D.C. seeking, under Section 337 of the Tariff Act of 1930, an exclusion order barring the importation by Carsem of infringing products. We also filed a complaint against Carsem in the U.S. District Court for the Northern District of California, alleging patent infringement and seeking an injunction, damages and costs. This District Court action has been stayed pending resolution of the ITC case. The ITC determined that certain Carsem Dual and Quad Flat No-Lead Packages infringe some patent claims of Amkor's U.S. Patent No. 6,433,277 (the "277 Patent") but that these infringed claims are invalid and, as a result, there is no violation of the Tariff Act. We appealed the ITC's ruling of invalidity for the claims of the 277 Patent to the U.S. Court of Appeals for the Federal Circuit (the "Federal Circuit"). In 2012, the Federal Circuit reversed the ITC's determination of invalidity on the 277 Patent, denied Carsem's petition for a rehearing and remanded the matter to the ITC for further proceedings consistent with its ruling. In April 2014, the ITC made a final determination that Carsem violated Section 337 of the Tariff Act and issued a limited exclusion order barring Carsem from importing into the U.S. any of its products that infringe certain claims of the 277 Patent. In January 2013, in response to Carsem, Inc.’s requests for reexamination of the 277 Patent, the U.S. PTO issued an Office Action rejecting all of the 277 Patent claims as invalid. Amkor believes that all of the 277 Patent claims are valid and filed a response to the Office Action in March 2013 contesting this finding. In January 2014, the U.S. PTO issued an Office Action maintaining the rejection of all claims of the 277 Patent as invalid. Amkor continues to believe its claims are valid and filed a response to the Office Action in March 2014.

16. Commitments and Contingencies

We have a letter of credit sub-facility of $25.0 million under our $150.0 million senior secured revolving credit facility that matures in June 2017. As of March 31, 2014, we had $0.4 million of standby letters of credit outstanding and had an additional $24.6 million available for letters of credit. Such standby letters of credit are used in the ordinary course of our business and are collateralized by our cash balances.

We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers' specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial.

Legal Proceedings

We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to make a determination as to the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. Except as indicated below, we believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future.

In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Proceedings with Tessera, Inc.

Since March 2006, we have been involved in several proceedings with Tessera Technologies, Inc. (“Tessera”) related to a license agreement (the “License Agreement”) entered into in 1996 between Tessera and our predecessor. The proceedings generally involve disputes about whether or not Amkor owes Tessera royalties under the License Agreement with respect to certain packages and the termination of the License Agreement. The main proceeding that is pending is with the International Court of Arbitration of the International Chamber of Commerce (the “ICC”) captioned Amkor Technology, Inc. v. Tessera, Inc. (the “2009 Arbitration”), which we initiated in August 2009. In that proceeding, the ICC arbitration panel has previously ruled that royalties are due to Tessera with respect to certain asserted patents and packages and that the License Agreement was terminated by Tessera as of February 17, 2011. The arbitration panel reserved for later decision the issues of the amount of royalties and pre-judgment interest due, and the allocation of costs. The other pending arbitration proceedings with Tessera include a request for arbitration by Tessera filed in May 2011 seeking undisclosed damages and a declaration that the License Agreement had been terminated, and a continuation of the 2009 proceeding related to three additional U.S. patents.

In July 2012, Tessera filed a complaint in the U.S. District Court for the District of Delaware. The complaint seeks injunctive relief and damages with respect to Amkor's alleged infringement of one of the U.S. patents (U.S. Patent No. 6,046,076, the "'076 patent") that the arbitration panel found to be royalty bearing in the 2009 Arbitration. In November 2013, the parties agreed to stay the Delaware litigation.

In February 2013, we filed a petition in the Superior Court for San Francisco County to vacate or correct a portion of the arbitration panel’s interim order relating to the panel’s authority to award royalties for the period after the termination of the License Agreement. The Superior Court has denied our request and we have appealed that decision to the California First District Court of Appeal.

In April 2013, we initiated an inter partes review (the “IPR”) proceeding with the Patent Trial and Appeal Board at the United States Patent and Trademark Office (“U.S. PTO”), requesting it to find certain claims of the ‘076 patent unpatentable, including the two claims we were found to practice during the 2009 Arbitration. In October 2013, the U.S. PTO determined that there is a reasonable likelihood that we will prevail in challenging those claims and certain others. Tessera has challenged the IPR proceeding and is expected to continue with such efforts. The IPR is scheduled to go forward on the merits with a hearing in May 2014.

In October 2013, January 2014 and March 2014, the arbitration panel issued additional interim orders which included, among other things, some substantive findings concerning the calculation of royalties under the License Agreement. In February 2014, Tessera filed a motion with the arbitration panel to enjoin us from proceeding with the IPR. We filed a response with the arbitration panel requesting it to deny Tessera's motion and to stay a portion of the 2009 Arbitration pending final resolution of the IPR proceeding. The arbitration panel denied both Tessera's motion and our request for a stay in March 2014.

We expect the arbitration panel to award Tessera royalties of $113 million plus interest. Most of the royalties claimed by Tessera relate to Amkor's alleged use of the ‘076 patent and the period following termination of the License Agreement. Any award by the arbitration panel must be confirmed by the courts before Tessera can enforce the award against Amkor, and we believe that a favorable outcome in the IPR or in the other pending proceedings may materially and adversely impact Tessera’s ability to confirm and collect on any final award by the arbitration panel and other claims for damages.

As a result of recent developments, the potential impact of the IPR proceeding on any award by the arbitration panel, and our position regarding potential royalties due to Tessera following the termination of the License Agreement, we reduced our estimate of the possible range of royalties due to Tessera in the 2009 Arbitration to be from $11 million to $113 million (net of royalties previously paid in 2012 and excluding interest). Our accrual for these royalties was $43.3 million at December 31, 2013. Although we have reduced our estimate of the low end of the range of possible royalties due, we have made a determination not to reduce our accrual due to the inherent uncertainty of the outcome in the various proceedings.

The ultimate amount of damages and interest we may owe to Tessera in connection with the several pending proceedings could be more or less than our estimate of the possible range of royalties due in the 2009 Arbitration, and could be more or less than the amount we expect the arbitration panel to award. The final outcome of our litigation with Tessera depends upon a number of complex factors, including whether we receive a favorable ruling in the above proceedings and other factors. We may adjust our accrual as information develops or upon the issuance of new rulings. As of March 31, 2014, we have $4.9 million accrued for interest related to these royalties, and we expect to record our estimate of interest accruing with the passage of time. We strongly dispute Tessera's claims in these proceedings and intend to vigorously defend against them. However, the final outcome of these matters is uncertain, and an adverse result could have a material adverse effect on our results of operations, financial condition and cash flows.

Amkor Technology, Inc. v. Carsem (M) Sdn Bhd, Carsem Semiconductor Sdn Bhd, and Carsem Inc.

Since November 2003, we have been involved in several proceedings against Carsem (M) Sdn Bhd, Carsem Semiconductor Sdn Bhd, and Carsem Inc. (collectively “Carsem”) in which we allege that with its Carsem Dual and Quad Flat No-Lead Packages, Carsem has infringed on one or more of our MicroLeadFrame packaging technology patent claims. We initiated the action with the U.S International Trade Commission (the “ITC”) in Washington, D.C. seeking, under Section 337 of the Tariff Act of 1930, an exclusion order barring the importation by Carsem of infringing products. We also filed a complaint against Carsem in the U.S. District Court for the Northern District of California, alleging patent infringement and seeking an injunction, damages and costs. This District Court action has been stayed pending resolution of the ITC case.

The ITC determined that certain Carsem Dual and Quad Flat No-Lead Packages infringe some patent claims of Amkor's U.S. Patent No. 6,433,277 (the "277 Patent") but that these infringed claims are invalid and, as a result, there is no violation of the Tariff Act. We appealed the ITC's ruling of invalidity for the claims of the 277 Patent to the U.S. Court of Appeals for the Federal Circuit (the "Federal Circuit").

In 2012, the Federal Circuit reversed the ITC's determination of invalidity on the 277 Patent, denied Carsem's petition for a rehearing and remanded the matter to the ITC for further proceedings consistent with its ruling.

In April 2014, the ITC made a final determination that Carsem violated Section 337 of the Tariff Act and issued a limited exclusion order barring Carsem from importing into the U.S. any of its products that infringe certain claims of the 277 Patent.

In January 2013, in response to Carsem, Inc.’s requests for reexamination of the 277 Patent, the U.S. PTO issued an Office Action rejecting all of the 277 Patent claims as invalid. Amkor believes that all of the 277 Patent claims are valid and filed a response to the Office Action in March 2013 contesting this finding. In January 2014, the U.S. PTO issued an Office Action maintaining the rejection of all claims of the 277 Patent as invalid. Amkor continues to believe its claims are valid and filed a response to the Office Action in March 2014.