Loss on Impairment	12 Months Ended
Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Loss on Impairment	Note 6— Loss on Impairment Asset Impairments In connection with the preparation of the consolidated financial statements included in this Annual Report, consistent with our accounting policies discussed in “Note 1— Organization and Significant Accounting Policies,” we evaluate our property and equipment for impairment whenever there are changes in facts which suggest that the value of the asset is not recoverable. In connection with the preparation of our financial statements for the year ended December 31, 2018, we conducted a review of our fleet. The review included an assessment of certain assumptions, including future marketability of each unit in light of its current technical specifications. Assumptions used in our assessment included, but were not limited to, timing of future contract awards and expected operating dayrates, operating costs, utilization rates, discount rates, capital expenditures, reactivation costs, estimated economic useful lives and, in certain cases, our belief that a drilling unit is no longer marketable and is unlikely to return to service. During the years ended December 31, 2018, 2017, and 2016, we recognized a non-cash loss on impairment of $802.1 million, $121.6 million and $1.5 billion, respectively, related to certain rigs and related capital spares. Based upon our impairment analysis, we impaired the carrying values to estimated fair values for the Noble Bully I, Noble Dave Beard, Noble Gene House, Noble Joe Beall, Noble Paul Romano, and certain capital spare equipment. During the year ended December 31, 2018, impairment charges related to these units and certain capital spare equipment were approximately $802.1 million. For our impaired units, we estimated the fair values of these units by applying the income valuation approach utilizing significant unobservable inputs, representative of a Level 3 fair value measurement. During the year ended December 31, 2018, we recognized a $550.3 million impairment on the Noble Bully I, of which $250.3 million is attributable to our joint venture partner. See “Note 2— Consolidated Joint Ventures” for additional information. During the year ended December 31, 2017, we identified indicators that certain assets in our fleet might not be recoverable. Such indicators included additional customer suspensions of drilling programs, contract cancellations, a further reduction in the number of new contract opportunities, resulting in reduced drilling contracts, and our belief that a drilling unit is no longer marketable and is unlikely to return to service. As a result, we determined that the carrying amounts of the Noble Amos Runner, Noble Alan Hay, Noble David Tinsley and certain capital spares were impaired and recorded an impairment charge of approximately $121.6 million. During the year ended December 31, 2016, in connection with our impairment analysis, we impaired the carrying values to estimated fair values for the Noble Amos Runner, Noble Clyde Boudreaux and Noble Dave Beard and recorded a charge of $1.0 billion related to these units. In addition, we concluded that the semisubmersible, the Noble Homer Ferrington, and certain capital spare equipment would not be utilized in the foreseeable future, and we recognized impairment charges of approximately $120.1 million and $170.5 million, respectively. Further, we decided to retire our semisubmersible, Noble Max Smith, which was sold for $1.2 million after we recognized an impairment charge during the year of approximately $164.8 million.

Note 6— Loss on Impairment

Asset Impairments

In connection with the preparation of the consolidated financial statements included in this Annual Report, consistent with our accounting policies discussed in “Note 1— Organization and Significant Accounting Policies,” we evaluate our property and equipment for impairment whenever there are changes in facts which suggest that the value of the asset is not recoverable. In connection with the preparation of our financial statements for the year ended December 31, 2018, we conducted a review of our fleet. The review included an assessment of certain assumptions, including future marketability of each unit in light of its current technical specifications. Assumptions used in our assessment included, but were not limited to, timing of future contract awards and expected operating dayrates, operating costs, utilization rates, discount rates, capital expenditures, reactivation costs, estimated economic useful lives and, in certain cases, our belief that a drilling unit is no longer marketable and is unlikely to return to service.

During the years ended December 31, 2018, 2017, and 2016, we recognized a non-cash loss on impairment of $802.1 million, $121.6 million and $1.5 billion, respectively, related to certain rigs and related capital spares.

Based upon our impairment analysis, we impaired the carrying values to estimated fair values for the Noble Bully I, Noble Dave Beard, Noble Gene House, Noble Joe Beall, Noble Paul Romano, and certain capital spare equipment. During the year ended December 31, 2018, impairment charges related to these units and certain capital spare equipment were approximately $802.1 million. For our impaired units, we estimated the fair values of these units by applying the income valuation approach utilizing significant unobservable inputs, representative of a Level 3 fair value measurement. During the year ended December 31, 2018, we recognized a $550.3 million impairment on the Noble Bully I, of which $250.3 million is attributable to our joint venture partner. See “Note 2— Consolidated Joint Ventures” for additional information.

During the year ended December 31, 2017, we identified indicators that certain assets in our fleet might not be recoverable. Such indicators included additional customer suspensions of drilling programs, contract cancellations, a further reduction in the number of new contract opportunities, resulting in reduced drilling contracts, and our belief that a drilling unit is no longer marketable and is unlikely to return to service. As a result, we determined that the carrying amounts of the Noble Amos Runner, Noble Alan Hay, Noble David Tinsley and certain capital spares were impaired and recorded an impairment charge of approximately $121.6 million.

During the year ended December 31, 2016, in connection with our impairment analysis, we impaired the carrying values to estimated fair values for the Noble Amos Runner, Noble Clyde Boudreaux and Noble Dave Beard and recorded a charge of $1.0 billion related to these units. In addition, we concluded that the semisubmersible, the Noble Homer Ferrington, and certain capital spare equipment would not be utilized in the foreseeable future, and we recognized impairment charges of approximately $120.1 million and $170.5 million, respectively. Further, we decided to retire our semisubmersible, Noble Max Smith, which was sold for $1.2 million after we recognized an impairment charge during the year of approximately $164.8 million.