Property, Plant and Equipment	9 Months Ended
Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	4. Property, Plant and Equipment Diamond Offshore Sale of Assets In February of 2016, Diamond Offshore entered into a ten-year agreement with a subsidiary of GE Oil & Gas (“GE”) to provide services with respect to certain blowout preventer and related well control equipment on four newly-built drillships. Such services include management of maintenance, certification and reliability with respect to such equipment. In connection with the contractual services agreement with GE, Diamond Offshore will sell the well control equipment to a GE affiliate and subsequently lease back such equipment pursuant to separate ten-year operating leases. During the nine months ended September 30, 2016, Diamond Offshore completed three sale and leaseback transactions and received $158 million in proceeds, which was less than the carrying value of the equipment. The resulting difference was recorded as prepaid rent with no gain or loss recognized on the transactions, and will be amortized over the terms of the operating leases. Future commitments under the operating leases and contractual services agreements are estimated to aggregate approximately $491 million over the term of the agreements. Diamond Offshore expects to complete the remaining sale and leaseback transaction in the fourth quarter of 2016. Asset Impairments During the second quarter of 2016, in response to the continuing decline in industry-wide utilization for semisubmersible rigs, further exacerbated by additional and more frequent contract cancelations by customers, declining dayrates, as well as the results of a third-party strategic review of Diamond Offshore’s long-term business plan completed in the second quarter of 2016, Diamond Offshore reassessed its projections for a recovery in the offshore drilling market. As a result, Diamond Offshore concluded that an expected market recovery is now likely further in the future than had previously been estimated. Consequently, Diamond Offshore believes its cold-stacked rigs, as well as those rigs expected to be cold-stacked in the near term after they come off contract, will likely remain cold-stacked for an extended period of time. Diamond Offshore also believes that the re-entry costs for these rigs will be higher than previously estimated, negatively impacting the undiscounted, probability-weighted cash flow projections utilized in its impairment analysis. In addition, in response to the declining market, Diamond Offshore also reduced anticipated market pricing and expected utilization of these rigs after reactivation. In the second quarter of 2016, Diamond Offshore evaluated 15 of its drilling rigs with indications that their carrying amounts may not be recoverable. Based on updated assumptions and analyses, Diamond Offshore determined that the carrying values of eight of these rigs, consisting of three ultra-deepwater, three deepwater and two mid-water semisubmersible rigs, were impaired. Diamond Offshore estimated the fair value of the eight impaired rigs using an income approach. The fair value of each rig was estimated based on a calculation of the rig’s discounted future net cash flows over its remaining economic life, which utilized significant unobservable inputs, including, but not limited to, assumptions related to estimated dayrate revenue, rig utilization, estimated reactivation and regulatory survey costs, as well as estimated proceeds that may be received on ultimate disposition of the rig. The fair value estimates were representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used. During the second quarter of 2016, Diamond Offshore recognized an impairment loss of $672 million ($263 million after tax and noncontrolling interests). In the third quarter of 2016, Diamond Offshore evaluated nine of its drilling rigs with indications that their carrying amounts may not be recoverable. Based on its assumptions and analyses, Diamond Offshore determined that the carrying values of these rigs were not impaired. If market fundamentals in the offshore oil and gas industry deteriorate further, Diamond Offshore may be required to recognize additional impairment losses in future periods. Diamond Offshore recognized aggregate impairment losses of $2 million ($1 million after tax and noncontrolling interests) and $361 million ($159 million after tax and noncontrolling interests) for the three and nine months ended September 30, 2015. See Note 6 of the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 for further discussion of Diamond Offshore’s 2015 asset impairments.

4. Property, Plant and Equipment

Diamond Offshore

Sale of Assets

In February of 2016, Diamond Offshore entered into a ten-year agreement with a subsidiary of GE Oil & Gas (“GE”) to provide services with respect to certain blowout preventer and related well control equipment on four newly-built drillships. Such services include management of maintenance, certification and reliability with respect to such equipment. In connection with the contractual services agreement with GE, Diamond Offshore will sell the well control equipment to a GE affiliate and subsequently lease back such equipment pursuant to separate ten-year operating leases. During the nine months ended September 30, 2016, Diamond Offshore completed three sale and leaseback transactions and received $158 million in proceeds, which was less than the carrying value of the equipment. The resulting difference was recorded as prepaid rent with no gain or loss recognized on the transactions, and will be amortized over the terms of the operating leases. Future commitments under the operating leases and contractual services agreements are estimated to aggregate approximately $491 million over the term of the agreements. Diamond Offshore expects to complete the remaining sale and leaseback transaction in the fourth quarter of 2016.

Asset Impairments

During the second quarter of 2016, in response to the continuing decline in industry-wide utilization for semisubmersible rigs, further exacerbated by additional and more frequent contract cancelations by customers, declining dayrates, as well as the results of a third-party strategic review of Diamond Offshore’s long-term business plan completed in the second quarter of 2016, Diamond Offshore reassessed its projections for a recovery in the offshore drilling market. As a result, Diamond Offshore concluded that an expected market recovery is now likely further in the future than had previously been estimated. Consequently, Diamond Offshore believes its cold-stacked rigs, as well as those rigs expected to be cold-stacked in the near term after they come off contract, will likely remain cold-stacked for an extended period of time. Diamond Offshore also believes that the re-entry costs for these rigs will be higher than previously estimated, negatively impacting the undiscounted, probability-weighted cash flow projections utilized in its impairment analysis. In addition, in response to the declining market, Diamond Offshore also reduced anticipated market pricing and expected utilization of these rigs after reactivation. In the second quarter of 2016, Diamond Offshore evaluated 15 of its drilling rigs with indications that their carrying amounts may not be recoverable. Based on updated assumptions and analyses, Diamond Offshore determined that the carrying values of eight of these rigs, consisting of three ultra-deepwater, three deepwater and two mid-water semisubmersible rigs, were impaired.

Diamond Offshore estimated the fair value of the eight impaired rigs using an income approach. The fair value of each rig was estimated based on a calculation of the rig’s discounted future net cash flows over its remaining economic life, which utilized significant unobservable inputs, including, but not limited to, assumptions related to estimated dayrate revenue, rig utilization, estimated reactivation and regulatory survey costs, as well as estimated proceeds that may be received on ultimate disposition of the rig. The fair value estimates were representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used. During the second quarter of 2016, Diamond Offshore recognized an impairment loss of $672 million ($263 million after tax and noncontrolling interests).

In the third quarter of 2016, Diamond Offshore evaluated nine of its drilling rigs with indications that their carrying amounts may not be recoverable. Based on its assumptions and analyses, Diamond Offshore determined that the carrying values of these rigs were not impaired. If market fundamentals in the offshore oil and gas industry deteriorate further, Diamond Offshore may be required to recognize additional impairment losses in future periods.

Diamond Offshore recognized aggregate impairment losses of $2 million ($1 million after tax and noncontrolling interests) and $361 million ($159 million after tax and noncontrolling interests) for the three and nine months ended September 30, 2015. See Note 6 of the Consolidated Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 for further discussion of Diamond Offshore’s 2015 asset impairments.