Impairments	12 Months Ended
Dec. 31, 2016
Impairments
Impairments	Note 6—Impairments Assets held for sale—In the year ended December 31, 2016, we recognized an aggregate loss of $41 million ($39 million, or $0.10 per diluted share, net of tax), associated with the impairment of the deepwater floaters M.G. Hulme, Jr. and Sedco 702 and the midwater floaters GSF Rig 140, Sedco 704, Transocean Driller, Transocean John Shaw and Transocean Winner, along with related and other equipment, which were classified as assets held for sale at the time of impairment. In the year ended December 31, 2015, we recognized an aggregate loss of $700 million ($585 million, or $1.60 per diluted share, net of tax) associated with the impairment of the ultra‑deepwater floaters Deepwater Expedition and GSF Explorer, the deepwater floaters Deepwater Navigator, Discoverer Seven Seas, GSF Celtic Sea, Sedco 707 and Transocean Rather and the midwater floaters GSF Aleutian Key, GSF Arctic III, GSF Grand Banks, GSF Rig 135, Transocean Amirante and Transocean Legend, along with related and other equipment, which were classified as assets held for sale at the time of impairment. In the year ended December 31, 2014, we recognized an aggregate loss of $268 million ($221 million, or $0.60 per diluted share, net of tax) associated with the impairment of the deepwater floaters Discoverer Seven Seas, Sedco 709, Sedco 710 and Sovereign Explorer, the midwater floaters C. Kirk Rhein, Jr., Falcon 100, GSF Arctic I, J.W. McLean, Sedco 601, Sedco 700, Sedco 703 and Sedneth 701 and the high‑specification jackups GSF Magellan and GSF Monitor, along with related equipment, which were classified as assets held for sale at the time of impairment. We measured the impairment of the drilling units and related equipment as the amount by which the carrying amount exceeded the estimated fair value less costs to sell. We estimated the fair value of the assets using significant other observable inputs, representative of Level 2 fair value measurements, including indicative market values for the drilling units and related equipment to be sold for scrap value or, in the case of GSF Magellan and GSF Monitor, binding sale and purchase agreements for the drilling units and related equipment. If we commit to plans to sell additional rigs for values below the respective carrying amounts, we may be required to recognize additional losses in future periods associated with the impairment of such assets. Assets held and used—During the year ended December 31, 2016, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included a reduction of projected dayrates and an extension to the currently low utilization rates. As a result of our testing, we determined that the carrying amount of our deepwater floater asset group was impaired. In the year ended December 31, 2016, we recognized a loss of $52 million ($0.14 per diluted share) which had no tax effect, associated with the impairment of the deepwater floater asset group. During the year ended December 31, 2015, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included a reduction in the number of new contract opportunities, customer suspensions of drilling programs, early contract terminations and cancellations and low dayrate fixtures. Our deepwater floater and midwater floater asset groups, in particular, experienced significant declines in projected dayrates and utilization caused by increased competition and marginalization of some of the less capable drilling units. As a result of our testing, we determined that the carrying amounts of the deepwater floater and the midwater floater asset groups were impaired. In the year ended December 31, 2015, we recognized losses of $507 million ($481 million, or $1.31 per diluted share, net of tax) and $668 million ($654 million, or $1.78 per diluted share, net of tax) associated with the impairment of the deepwater floater asset group and the midwater floater asset group, respectively, including losses of $41 million and $11 million, respectively, associated with construction in progress for each asset group. During the year ended December 31, 2014, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included low dayrate fixtures, partly caused by more technologically advanced drilling units competing with less capable drilling units, and projected declines in dayrates and utilization, particularly for the deepwater floater asset group. As a result of our testing, we determined that the carrying amount of the deepwater floater asset group was impaired. In the year ended December 31, 2014, we recognized a loss of $788 million ($693 million, or $1.91 per diluted share, net of tax) associated with the impairment of the deepwater floater asset group. We estimated the fair value of the asset groups by applying a combination of income, market and cost approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. Our estimates of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. If we experience increasingly unfavorable changes to actual or anticipated dayrates or other impairment indicators, or if we are unable to secure new or extended contracts for our active units or the reactivation of any of our stacked units, we may be required to recognize additional losses in future periods as a result of impairments of the carrying amount of one or more of our asset groups. Goodwill—During the year ended December 31, 2014, we noted rapid and significant declines in the market value of our stock, oil and natural gas prices and actual and projected declines in dayrates and utilization. We identified these as indicators that the fair value of our goodwill could have fallen below its carrying amount. As a result, we performed interim goodwill impairment tests and determined that the goodwill associated with our contract drilling services reporting unit was fully impaired. In the year ended December 31, 2014, we recognized an aggregate loss of $3.0 billion associated with the full impairment of the carrying amount of our goodwill, which had no tax effect. We determined that, of the $3.0 billion aggregate loss, $2.9 billion ($8.02 per diluted share) was attributable to controlling interest and $74 million was attributable to noncontrolling interest. We estimated the implied fair value of the goodwill using a variety of valuation methods, including the income and market approaches. Our estimate of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future oil and natural gas prices, projected demand for our services, rig availability and dayrates.

Note 6—Impairments

Assets held for sale—In the year ended December 31, 2016, we recognized an aggregate loss of $41 million ($39 million, or $0.10 per diluted share, net of tax), associated with the impairment of the deepwater floaters M.G. Hulme, Jr. and Sedco 702 and the midwater floaters GSF Rig 140, Sedco 704, Transocean Driller, Transocean John Shaw and Transocean Winner, along with related and other equipment, which were classified as assets held for sale at the time of impairment.

In the year ended December 31, 2015, we recognized an aggregate loss of $700 million ($585 million, or $1.60 per diluted share, net of tax) associated with the impairment of the ultra‑deepwater floaters Deepwater Expedition and GSF Explorer, the deepwater floaters Deepwater Navigator, Discoverer Seven Seas, GSF Celtic Sea, Sedco 707 and Transocean Rather and the midwater floaters GSF Aleutian Key, GSF Arctic III, GSF Grand Banks, GSF Rig 135, Transocean Amirante and Transocean Legend, along with related and other equipment, which were classified as assets held for sale at the time of impairment.

In the year ended December 31, 2014, we recognized an aggregate loss of $268 million ($221 million, or $0.60 per diluted share, net of tax) associated with the impairment of the deepwater floaters Discoverer Seven Seas, Sedco 709, Sedco 710 and Sovereign Explorer, the midwater floaters C. Kirk Rhein, Jr., Falcon 100, GSF Arctic I, J.W. McLean, Sedco 601, Sedco 700, Sedco 703 and Sedneth 701 and the high‑specification jackups GSF Magellan and GSF Monitor, along with related equipment, which were classified as assets held for sale at the time of impairment.

We measured the impairment of the drilling units and related equipment as the amount by which the carrying amount exceeded the estimated fair value less costs to sell. We estimated the fair value of the assets using significant other observable inputs, representative of Level 2 fair value measurements, including indicative market values for the drilling units and related equipment to be sold for scrap value or, in the case of GSF Magellan and GSF Monitor, binding sale and purchase agreements for the drilling units and related equipment. If we commit to plans to sell additional rigs for values below the respective carrying amounts, we may be required to recognize additional losses in future periods associated with the impairment of such assets.

Assets held and used—During the year ended December 31, 2016, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included a reduction of projected dayrates and an extension to the currently low utilization rates. As a result of our testing, we determined that the carrying amount of our deepwater floater asset group was impaired. In the year ended December 31, 2016, we recognized a loss of $52 million ($0.14 per diluted share) which had no tax effect, associated with the impairment of the deepwater floater asset group.

During the year ended December 31, 2015, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included a reduction in the number of new contract opportunities, customer suspensions of drilling programs, early contract terminations and cancellations and low dayrate fixtures. Our deepwater floater and midwater floater asset groups, in particular, experienced significant declines in projected dayrates and utilization caused by increased competition and marginalization of some of the less capable drilling units. As a result of our testing, we determined that the carrying amounts of the deepwater floater and the midwater floater asset groups were impaired. In the year ended December 31, 2015, we recognized losses of $507 million ($481 million, or $1.31 per diluted share, net of tax) and $668 million ($654 million, or $1.78 per diluted share, net of tax) associated with the impairment of the deepwater floater asset group and the midwater floater asset group, respectively, including losses of $41 million and $11 million, respectively, associated with construction in progress for each asset group.

During the year ended December 31, 2014, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included low dayrate fixtures, partly caused by more technologically advanced drilling units competing with less capable drilling units, and projected declines in dayrates and utilization, particularly for the deepwater floater asset group. As a result of our testing, we determined that the carrying amount of the deepwater floater asset group was impaired. In the year ended December 31, 2014, we recognized a loss of $788 million ($693 million, or $1.91 per diluted share, net of tax) associated with the impairment of the deepwater floater asset group.

We estimated the fair value of the asset groups by applying a combination of income, market and cost approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. Our estimates of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. If we experience increasingly unfavorable changes to actual or anticipated dayrates or other impairment indicators, or if we are unable to secure new or extended contracts for our active units or the reactivation of any of our stacked units, we may be required to recognize additional losses in future periods as a result of impairments of the carrying amount of one or more of our asset groups.

Goodwill—During the year ended December 31, 2014, we noted rapid and significant declines in the market value of our stock, oil and natural gas prices and actual and projected declines in dayrates and utilization. We identified these as indicators that the fair value of our goodwill could have fallen below its carrying amount. As a result, we performed interim goodwill impairment tests and determined that the goodwill associated with our contract drilling services reporting unit was fully impaired. In the year ended December 31, 2014, we recognized an aggregate loss of $3.0 billion associated with the full impairment of the carrying amount of our goodwill, which had no tax effect. We determined that, of the $3.0 billion aggregate loss, $2.9 billion ($8.02 per diluted share) was attributable to controlling interest and $74 million was attributable to noncontrolling interest. We estimated the implied fair value of the goodwill using a variety of valuation methods, including the income and market approaches. Our estimate of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future oil and natural gas prices, projected demand for our services, rig availability and dayrates.