Stockholder Rights Plan	12 Months Ended
Dec. 31, 2015
Equity [Abstract]
Stockholder Rights Plan	Stockholder Rights Plan We have a stockholder rights plan, or the Rights Plan, established under the terms of a rights agreement dated December 21, 2006, as amended, with Computershare Trust Company N.A., as Rights Agent, or the Rights Agreement. The Rights Plan was initially intended to protect our stockholders from coercive takeover practices or takeover bids that are inconsistent with their best interests. However, in 2013 and 2015, the Board of Directors adopted amendments to the Rights Agreement, discussed below, intended to protect our substantial NOL carryforwards and related tax benefits. The Board of Directors also recommended, and on May 9, 2013 our stockholders approved, an amendment to our Restated Certificate of Incorporation, or the Protective Amendment, also intended to protect our NOL carryforwards and related tax benefits. NOL Protective Amendments to our Rights Plan On March 22, 2013, our Board of Directors approved an amendment to the Rights Agreement in an effort to protect our NOL carryforwards and related tax benefits. Our ability to use our NOLs could be substantially reduced if we experience an “ownership change,” as defined under Section 382 of the Internal Revenue Code of 1986, as amended (the "Code"), and the Rights Agreement has been designed to prevent such an “ownership change.” “Ownership changes” generally relate to the cumulative change in ownership among stockholders with an ownership interest of 5% or more (as determined under the Code’s rules) over a rolling three-year period. Our stockholders ratified, on an advisory basis, the March 22, 2013 amendment to our Rights Agreement at our 2013 annual meeting of stockholders. The Rights Agreement, as amended, provides that if any person becomes the beneficial owner of 4.9% or more of our common stock, stockholders other than the 4.9% triggering stockholder will have the right to purchase additional shares of our common stock at half the market price, thereby diluting the triggering stockholder; provided that stockholders whose beneficial ownership, as defined in Section 383 of the Code, exceeded 4.9% of our common stock outstanding on February 11, 2015 will not be deemed to have triggered the Rights Agreement, as amended, so long as they do not thereafter acquire additional common stock other than in certain specified exempt transactions. The Board of Directors approved an amendment to the Rights Agreement in February 2015 to align the definition of “Beneficial Owner” and “Beneficially Own” with Section 382 of the Code. The NOL protective provisions in the Rights Agreement adopted in 2013 were scheduled to expire on March 22, 2016 and the Rights Agreement was scheduled to expire on January 2, 2017. In connection with a required triennial review of the Rights Agreement, the Board of Directors approved, and on November 16, 2015 the Company entered into, another amendment to the Rights Agreement to extend the term of the Rights Agreement, as well as the NOL protective provisions adopted in 2013, to May 31, 2019, subject to other earlier termination events as described therein. Accordingly, the 4.9% threshold described above is now effective until the earlier of (i) May 31, 2019, (ii) the date on which our Board of Directors determines that the amendment is no longer necessary for the provision of certain tax benefits because of the repeal of Section 382 of the Code, (iii) the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as our Board determines that the amendment is no longer necessary for the preservation of tax benefits. The rights issued pursuant to the Rights Agreement will expire on May 31, 2019. However, our Board of Directors has the power to accelerate or extend the expiration date of the rights. In addition, a board committee composed solely of independent directors reviews the Rights Agreement at least once every three years to determine whether to modify the Rights Plan in light of all relevant factors. This review was most recently conducted in November 2015. The next review is required by the end of 2018. Protective Amendment to Charter On May 9, 2013, we filed an amendment to our Restated Certificate of Incorporation, or the Protective Amendment, that restricts certain transfers of our common stock. The Protective Amendment is intended to protect the tax benefits of our NOL carryforwards. See Note 15 for a description of our NOL carryforwards. Subject to certain limited exceptions, the Protective Amendment's transfer restrictions restrict any person from transferring our common stock (or any interest in our common stock) if the transfer would result in a stockholder (or several stockholders, in the aggregate, who hold their stock as a “group” under Section 382 of the Code) owning 4.9% or more of our common stock. Any direct or indirect transfer attempted in violation of the Protective Amendment would be void as of the date of the prohibited transfer as to the purported transferee, and the purported transferee would not be recognized as the owner of the shares attempted to be owned in violation of the Protective Amendment for any purpose, including for purposes of voting and receiving dividends or other distributions in respect of that common stock, or in the case of options, receiving our common stock in respect of their exercise. The Protective Amendment is effective until the earlier of (i) May 9, 2016, (ii) the repeal of Section 382 of the Code if our Board of Directors determines that the Protective Amendment is no longer necessary for the preservation of tax benefits, (iii) the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as determined by our Board of Directors pursuant to the Protective Amendment. On November 12, 2015, our Board of Directors also recommended that stockholders vote to extend the Protective Amendment until May 31, 2019 (subject to other earlier termination events as described in the Protective Amendment). Treatment of Berkshire Hathaway under Rights Agreement and Protective Amendment Berkshire Hathaway and certain of its affiliates may acquire beneficial ownership of up to 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in the Protective Amendment or Rights Agreement, and may acquire beneficial ownership of more than 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in the Protective Amendment or Rights Agreement through an offer to purchase all of our common stock that remains open for at least 60 days, in each case subject to specified exceptions.

Stockholder Rights Plan

We have a stockholder rights plan, or the Rights Plan, established under the terms of a rights agreement dated December 21, 2006, as amended, with Computershare Trust Company N.A., as Rights Agent, or the Rights Agreement. The Rights Plan was initially intended to protect our stockholders from coercive takeover practices or takeover bids that are inconsistent with their best interests. However, in 2013 and 2015, the Board of Directors adopted amendments to the Rights Agreement, discussed below, intended to protect our substantial NOL carryforwards and related tax benefits. The Board of Directors also recommended, and on May 9, 2013 our stockholders approved, an amendment to our Restated Certificate of Incorporation, or the Protective Amendment, also intended to protect our NOL carryforwards and related tax benefits.

NOL Protective Amendments to our Rights Plan

On March 22, 2013, our Board of Directors approved an amendment to the Rights Agreement in an effort to protect our NOL carryforwards and related tax benefits. Our ability to use our NOLs could be substantially reduced if we experience an “ownership change,” as defined under Section 382 of the Internal Revenue Code of 1986, as amended (the "Code"), and the Rights Agreement has been designed to prevent such an “ownership change.” “Ownership changes” generally relate to the cumulative change in ownership among stockholders with an ownership interest of 5% or more (as determined under the Code’s rules) over a rolling three-year period. Our stockholders ratified, on an advisory basis, the March 22, 2013 amendment to our Rights Agreement at our 2013 annual meeting of stockholders. The Rights Agreement, as amended, provides that if any person becomes the beneficial owner of 4.9% or more of our common stock, stockholders other than the 4.9% triggering stockholder will have the right to purchase additional shares of our common stock at half the market price, thereby diluting the triggering stockholder; provided that stockholders whose beneficial ownership, as defined in Section 383 of the Code, exceeded 4.9% of our common stock outstanding on February 11, 2015 will not be deemed to have triggered the Rights Agreement, as amended, so long as they do not thereafter acquire additional common stock other than in certain specified exempt transactions. The Board of Directors approved an amendment to the Rights Agreement in February 2015 to align the definition of “Beneficial Owner” and “Beneficially Own” with Section 382 of the Code.

The NOL protective provisions in the Rights Agreement adopted in 2013 were scheduled to expire on March 22, 2016 and the Rights Agreement was scheduled to expire on January 2, 2017. In connection with a required triennial review of the Rights Agreement, the Board of Directors approved, and on November 16, 2015 the Company entered into, another amendment to the Rights Agreement to extend the term of the Rights Agreement, as well as the NOL protective provisions adopted in 2013, to May 31, 2019, subject to other earlier termination events as described therein. Accordingly, the 4.9% threshold described above is now effective until the earlier of (i) May 31, 2019, (ii) the date on which our Board of Directors determines that the amendment is no longer necessary for the provision of certain tax benefits because of the repeal of Section 382 of the Code, (iii) the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as our Board determines that the amendment is no longer necessary for the preservation of tax benefits.

The rights issued pursuant to the Rights Agreement will expire on May 31, 2019. However, our Board of Directors has the power to accelerate or extend the expiration date of the rights. In addition, a board committee composed solely of independent directors reviews the Rights Agreement at least once every three years to determine whether to modify the Rights Plan in light of all relevant factors. This review was most recently conducted in November 2015. The next review is required by the end of 2018.

Protective Amendment to Charter

On May 9, 2013, we filed an amendment to our Restated Certificate of Incorporation, or the Protective Amendment, that restricts certain transfers of our common stock. The Protective Amendment is intended to protect the tax benefits of our NOL carryforwards. See Note 15 for a description of our NOL carryforwards. Subject to certain limited exceptions, the Protective Amendment's transfer restrictions restrict any person from transferring our common stock (or any interest in our common stock) if the transfer would result in a stockholder (or several stockholders, in the aggregate, who hold their stock as a “group” under Section 382 of the Code) owning 4.9% or more of our common stock. Any direct or indirect transfer attempted in violation of the Protective Amendment would be void as of the date of the prohibited transfer as to the purported transferee, and the purported transferee would not be recognized as the owner of the shares attempted to be owned in violation of the Protective Amendment for any purpose, including for purposes of voting and receiving dividends or other distributions in respect of that common stock, or in the case of options, receiving our common stock in respect of their exercise. The Protective Amendment is effective until the earlier of (i) May 9, 2016, (ii) the repeal of Section 382 of the Code if our Board of Directors determines that the Protective Amendment is no longer necessary for the preservation of tax benefits, (iii) the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as determined by our Board of Directors pursuant to the Protective Amendment. On November 12, 2015, our Board of Directors also recommended that stockholders vote to extend the Protective Amendment until May 31, 2019 (subject to other earlier termination events as described in the Protective Amendment).

Treatment of Berkshire Hathaway under Rights Agreement and Protective Amendment

Berkshire Hathaway and certain of its affiliates may acquire beneficial ownership of up to 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in the Protective Amendment or Rights Agreement, and may acquire beneficial ownership of more than 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in the Protective Amendment or Rights Agreement through an offer to purchase all of our common stock that remains open for at least 60 days, in each case subject to specified exceptions.