Shareholders' Equity	6 Months Ended
Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity Share repurchase program On April 26, 2018, our Board of Directors authorized a share repurchase program under which we may repurchase up to $200 million of our common stock through the end of 2019. Repurchases may be made from time to time on the open market or through privately negotiated transactions. The repurchase program may be suspended for periods or discontinued at any time. During the second quarter, we repurchased approximately 9.2 million shares of our common stock at a weighted average price per share of $10.88, which included commissions. Change in accounting principle As described in Note 2 - “New Accounting Pronouncements,” during the first quarter of 2018 the updated guidance of “Recognition and Measurement of Financial Assets and Financial Liabilities” became effective. The application of this guidance resulted in an immaterial cumulative effect adjustment to our 2018 beginning accumulated other comprehensive (loss) income and retained earnings to recognize unrealized gains on equity securities. Shareholders Rights Agreement Our Amended and Restated Rights Agreement dated August 1, 2018 (“the 2018 Agreement”) seeks to diminish the risk that our ability to use our NOLs to reduce potential future federal income tax obligations may become substantially limited and to deter certain abusive takeover practices. The benefit of the NOLs would be substantially limited, and the timing of the usage of the NOLs could be substantially delayed, if we were to experience an “ownership change” as defined by Section 382 of the Internal Revenue Code. Under the 2018 Agreement, each outstanding share of our Common Stock is accompanied by one Right. The “Distribution Date” occurs on the earlier of ten days after a public announcement that a person has become an “Acquiring Person,” or ten business days after a person announces or begins a tender offer in which consummation of such offer would result in a person becoming an “Acquiring Person.” An “Acquiring Person” is any person that becomes, by itself or together with its affiliates and associates, a beneficial owner of 5% or more of the shares of our Common Stock then outstanding, but excludes, among others, certain exempt and grandfathered persons as defined in the Agreement. The Rights are not exercisable until the Distribution Date. Each Right will initially entitle shareholders to buy one-tenth of one share of our Common Stock at a Purchase Price of $45 per full share (equivalent to $4.50 for each one-tenth share), subject to adjustment. Each exercisable Right (subject to certain limitations) will entitle its holder to purchase, at the Rights’ then-current Purchase Price, a number of our shares of Common Stock (or if after the Shares Acquisition Date, we are acquired in a business combination, common shares of the acquiror) having a market value at the time equal to twice the Purchase Price. The Rights will expire on March 1, 2020, or earlier as described in the 2018 Agreement. The Rights are redeemable at a price of $0.001 per Right at any time prior to the time a person becomes an Acquiring Person. Other than certain amendments, the Board of Directors may amend the Rights in any respect without the consent of the holders of the Rights.

Shareholders’ Equity

Share repurchase program

On April 26, 2018, our Board of Directors authorized a share repurchase program under which we may repurchase up to $200 million of our common stock through the end of 2019. Repurchases may be made from time to time on the open market or through privately negotiated transactions. The repurchase program may be suspended for periods or discontinued at any time.

During the second quarter, we repurchased approximately 9.2 million shares of our common stock at a weighted average price per share of $10.88, which included commissions.

Change in accounting principle

As described in Note 2 - “New Accounting Pronouncements,” during the first quarter of 2018 the updated guidance of “Recognition and Measurement of Financial Assets and Financial Liabilities” became effective. The application of this guidance resulted in an immaterial cumulative effect adjustment to our 2018 beginning accumulated other comprehensive (loss) income and retained earnings to recognize unrealized gains on equity securities.

Shareholders Rights Agreement

Our Amended and Restated Rights Agreement dated August 1, 2018 (“the 2018 Agreement”) seeks to diminish the risk that our ability to use our NOLs to reduce potential future federal income tax obligations may become substantially limited and to deter certain abusive takeover practices. The benefit of the NOLs would be substantially limited, and the timing of the usage of the NOLs could be substantially delayed, if we were to experience an “ownership change” as defined by Section 382 of the Internal Revenue Code.

Under the 2018 Agreement, each outstanding share of our Common Stock is accompanied by one Right. The “Distribution Date” occurs on the earlier of ten days after a public announcement that a person has become an “Acquiring Person,” or ten business days after a person announces or begins a tender offer in which consummation of such offer would result in a person becoming an “Acquiring Person.” An “Acquiring Person” is any person that becomes, by itself or together with its affiliates and associates, a beneficial owner of 5% or more of the shares of our Common Stock then outstanding, but excludes, among others, certain exempt and grandfathered persons as defined in the Agreement. The Rights are not exercisable until the Distribution Date. Each Right will initially entitle shareholders to buy one-tenth of one share of our Common Stock at a Purchase Price of $45 per full share (equivalent to $4.50 for each one-tenth share), subject to adjustment. Each exercisable Right (subject to certain limitations) will entitle its holder to purchase, at the Rights’ then-current Purchase Price, a number of our shares of Common Stock (or if after the Shares Acquisition Date, we are acquired in a business combination, common shares of the acquiror) having a market value at the time equal to twice the Purchase Price. The Rights will expire on March 1, 2020, or earlier as described in the 2018 Agreement. The Rights are redeemable at a price of $0.001 per Right at any time prior to the time a person becomes an Acquiring Person. Other than certain amendments, the Board of Directors may amend the Rights in any respect without the consent of the holders of the Rights.