Debt (Notes)	6 Months Ended
Jun. 30, 2015
Debt Instrument [Line Items]
Debt Disclosure [Text Block]	Debt Senior Notes During the first quarter of 2015, we issued $700.0 million aggregate principal amount of unsecured 5.20% senior notes due 2025 (the “2025 Notes”) at a discount of $2.6 million and $400.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the “New 2044 Notes”) at a discount of $18.7 million in a public offering. Interest on the 2025 Notes is payable semiannually on March 15 and September 15 of each year commencing September 15, 2015. Interest on the New 2044 Notes is payable semiannually on April 1 and October 1 of each year commencing on April 1, 2015. The 2025 Notes were issued pursuant to the Indenture between us and Deutsche Bank Trust Company Americas, as trustee (the “Trustee”), dated March 17, 2011 (the “Base Indenture”), as supplemented by the Third Supplemental Indenture between us and the Trustee, dated as of March 12, 2015 (the “Third Supplemental Indenture”). The New 2044 Notes were issued as additional notes under the Base Indenture, as supplemented by the Second Supplemental Indenture between us and the Trustee, dated September 29, 2014 (the “Second Supplemental Indenture”), pursuant to which we previously issued $625.0 million aggregate principal amount of 5.75% senior notes due 2044 (the “Existing 2044 Notes”) in September 2014 (the Base Indenture, as amended and supplemented by the Second Supplemental Indenture and the Third Supplement Indenture, the “Indenture”). The New 2044 Notes and Existing 2044 Notes are treated as a single series of debt securities under the Indenture (collectively, the “2044 Notes”). We may redeem the 2025 Notes and 2044 Notes, in whole at any time or in part from time to time, prior to maturity. If we elect to redeem the 2025 Notes before the date that is three months prior to the maturity date or the 2044 Notes before the date that is six months prior to the maturity date, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest and a “make-whole” premium. If we elect to redeem the 2025 Notes or 2044 Notes on or after the aforementioned dates, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest, but are not required to pay a "make-whole" premium. The 2025 Notes, 2044 Notes and Indenture also contain customary events of default, including failure to pay principal or interest on the 2025 Notes or 2044 Notes when due, among others. The Indenture contains certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create liens on certain assets, enter into certain sale-leaseback transactions, enter into certain merger or consolidation transactions or transfers of all or substantially all of our assets. Redemption of 2016 Senior Notes and MARAD Obligations During 2011, we issued $1.0 billion of 3.25% senior notes with a maturity in 2016 (the “2016 Notes”). In March 2015, we commenced a cash tender offer (the “Tender Offer”) for the $1.0 billion outstanding aggregate principal amount of our 2016 Notes. Senior notes totaling $854.6 million were settled on March 12, 2015 for $878.0 million (excluding accrued interest) using a portion of the net proceeds from the public offering of the 2025 Notes and New 2044 Notes. Under the terms of the Tender Offer, we paid a premium totaling approximately $23.4 million, which approximates the “make-whole” premium that would have been required had we elected to redeem the debt. The premium was recorded as a loss on debt extinguishment and included in other, net in our condensed consolidated statement of operations for the six-month period ended June 30, 2015. Additionally, we wrote-off $1.7 million of unamortized debt discount and $1.5 million of unamortized debt issuance costs associated with the $854.6 million of notes tendered, resulting in a total pre-tax loss on debt extinguishment of $26.6 million. Concurrent with the settlement of the Tender Offer, we exercised our right to redeem the remaining 2016 Notes. In April 2015, we completed the redemption of the $145.4 million of 2016 Notes that remained outstanding using a portion of the net proceeds from the public offering of the 2025 Notes and New 2044 Notes. The redemption payment included a "make-whole" premium of $3.8 million which was recorded as a loss on debt extinguishment and included in other, net in our condensed consolidated statement of operations for the three-month and six-month periods ended June 30, 2015. In April 2015, we used the remaining net proceeds from our March 2015 public offering, together with cash on hand, to redeem $51.0 million of our 4.33% MARAD notes due 2016 and our 4.65% MARAD bonds due 2020 (the “MARAD Obligations”). We incurred additional losses on debt extinguishment of $3.1 million, which were included in other, net in our condensed consolidated statement of operations for the three-month and six-month periods ended June 30, 2015. These losses primarily consisted of a "make-whole" premium. In July 2015, we redeemed the remaining $14.3 million aggregate principal amount of the MARAD Obligations. Revolving Credit We have a $2.25 billion senior unsecured revolving credit facility with a syndicate of banks to be used for general corporate purposes with a term expiring on September 30, 2019 (the "Credit Facility"). Advances under the Credit Facility bear interest at Base Rate or LIBOR plus an applicable margin rate (currently 0.125% per annum for Base Rate advances and 1.125% per annum for LIBOR advances) depending on our credit rating. Amounts repaid may be re-borrowed during the term of the Credit Facility. We are required to pay a quarterly commitment fee (currently 0.125% per annum) on the undrawn portion of the $2.25 billion commitment which is also based on our credit rating. In addition to other customary restrictive covenants, the Credit Facility requires us to maintain a total debt to total capitalization ratio that is less than or equal to a specified percentage. In March 2015, we amended the Credit Facility to increase the percentage from 50% to 60%. We have the right, subject to receipt of commitments from new or existing lenders, to increase the commitments under the Credit Facility to an aggregate amount of up to $2.75 billion. We had no amounts outstanding under the Credit Facility as of June 30, 2015 and December 31, 2014.

Debt

Senior Notes

During the first quarter of 2015, we issued $700.0 million aggregate principal amount of unsecured 5.20% senior notes due 2025 (the “2025 Notes”) at a discount of $2.6 million and $400.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the “New 2044 Notes”) at a discount of $18.7 million in a public offering. Interest on the 2025 Notes is payable semiannually on March 15 and September 15 of each year commencing September 15, 2015. Interest on the New 2044 Notes is payable semiannually on April 1 and October 1 of each year commencing on April 1, 2015.

The 2025 Notes were issued pursuant to the Indenture between us and Deutsche Bank Trust Company Americas, as trustee (the “Trustee”), dated March 17, 2011 (the “Base Indenture”), as supplemented by the Third Supplemental Indenture between us and the Trustee, dated as of March 12, 2015 (the “Third Supplemental Indenture”). The New 2044 Notes were issued as additional notes under the Base Indenture, as supplemented by the Second Supplemental Indenture between us and the Trustee, dated September 29, 2014 (the “Second Supplemental Indenture”), pursuant to which we previously issued $625.0 million aggregate principal amount of 5.75% senior notes due 2044 (the “Existing 2044 Notes”) in September 2014 (the Base Indenture, as amended and supplemented by the Second Supplemental Indenture and the Third Supplement Indenture, the “Indenture”). The New 2044 Notes and Existing 2044 Notes are treated as a single series of debt securities under the Indenture (collectively, the “2044 Notes”).

We may redeem the 2025 Notes and 2044 Notes, in whole at any time or in part from time to time, prior to maturity. If we elect to redeem the 2025 Notes before the date that is three months prior to the maturity date or the 2044 Notes before the date that is six months prior to the maturity date, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest and a “make-whole” premium. If we elect to redeem the 2025 Notes or 2044 Notes on or after the aforementioned dates, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest, but are not required to pay a "make-whole" premium.

The 2025 Notes, 2044 Notes and Indenture also contain customary events of default, including failure to pay principal or interest on the 2025 Notes or 2044 Notes when due, among others. The Indenture contains certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create liens on certain assets, enter into certain sale-leaseback transactions, enter into certain merger or consolidation transactions or transfers of all or substantially all of our assets.

Redemption of 2016 Senior Notes and MARAD Obligations

During 2011, we issued $1.0 billion of 3.25% senior notes with a maturity in 2016 (the “2016 Notes”). In March 2015, we commenced a cash tender offer (the “Tender Offer”) for the $1.0 billion outstanding aggregate principal amount of our 2016 Notes. Senior notes totaling $854.6 million were settled on March 12, 2015 for $878.0 million (excluding accrued interest) using a portion of the net proceeds from the public offering of the 2025 Notes and New 2044 Notes. Under the terms of the Tender Offer, we paid a premium totaling approximately $23.4 million, which approximates the “make-whole” premium that would have been required had we elected to redeem the debt. The premium was recorded as a loss on debt extinguishment and included in other, net in our condensed consolidated statement of operations for the six-month period ended June 30, 2015. Additionally, we wrote-off $1.7 million of unamortized debt discount and $1.5 million of unamortized debt issuance costs associated with the $854.6 million of notes tendered, resulting in a total pre-tax loss on debt extinguishment of $26.6 million.

Concurrent with the settlement of the Tender Offer, we exercised our right to redeem the remaining 2016 Notes. In April 2015, we completed the redemption of the $145.4 million of 2016 Notes that remained outstanding using a portion of the net proceeds from the public offering of the 2025 Notes and New 2044 Notes. The redemption payment included a "make-whole" premium of $3.8 million which was recorded as a loss on debt extinguishment and included in other, net in our condensed consolidated statement of operations for the three-month and six-month periods ended June 30, 2015.

In April 2015, we used the remaining net proceeds from our March 2015 public offering, together with cash on hand, to redeem $51.0 million of our 4.33% MARAD notes due 2016 and our 4.65% MARAD bonds due 2020 (the “MARAD Obligations”). We incurred additional losses on debt extinguishment of $3.1 million, which were included in other, net in our condensed consolidated statement of operations for the three-month and six-month periods ended June 30, 2015. These losses primarily consisted of a "make-whole" premium.

In July 2015, we redeemed the remaining $14.3 million aggregate principal amount of the MARAD Obligations.

Revolving Credit

We have a $2.25 billion senior unsecured revolving credit facility with a syndicate of banks to be used for general corporate purposes with a term expiring on September 30, 2019 (the "Credit Facility"). Advances under the Credit Facility bear interest at Base Rate or LIBOR plus an applicable margin rate (currently 0.125% per annum for Base Rate advances and 1.125% per annum for LIBOR advances) depending on our credit rating. Amounts repaid may be re-borrowed during the term of the Credit Facility. We are required to pay a quarterly commitment fee (currently 0.125% per annum) on the undrawn portion of the $2.25 billion commitment which is also based on our credit rating. In addition to other customary restrictive covenants, the Credit Facility requires us to maintain a total debt to total capitalization ratio that is less than or equal to a specified percentage. In March 2015, we amended the Credit Facility to increase the percentage from 50% to 60%.

We have the right, subject to receipt of commitments from new or existing lenders, to increase the commitments under the Credit Facility to an aggregate amount of up to $2.75 billion. We had no amounts outstanding under the Credit Facility as of June 30, 2015 and December 31, 2014.