Impairment of Assets	6 Months Ended
Jun. 30, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Impairment of Assets	5. Impairment of Assets 2021 Impairment. At June 30, 2021, we evaluated four drilling rigs with indicators of impairment. Based on our assumptions and analysis at that time, we determined that the undiscounted probability-weighted cash flow for each rig was in excess of its respective carrying value. As a result, we concluded that no impairment of these rigs had occurred. No asset impairments were recorded for the period from April 24 through June 30, 2021. During the first quarter of 2021, we evaluated three of our drilling rigs with indicators of impairment. Based on our assumptions and analysis at that time, we determined that the carrying value of one of these rigs, for which we have concerns regarding future opportunities, was impaired (or the 2021 Impaired Rig). We estimated the fair value of the 2021 Impaired Rig using an income approach, whereby the fair value of the rig was estimated based on a calculation of the rig’s future net cash flows. These calculations utilized significant unobservable inputs, including management’s assumptions related to estimated dayrate revenue, rig utilization, estimated capital expenditures, repair and regulatory survey costs, as well as estimated proceeds that may be received on ultimate disposition of the rig. Our fair value estimate was representative of a Level 3 fair value measurement due to the significant level of estimation involved and the lack of transparency as to the inputs used. We recorded asset impairments aggregating $197.0 million for the period from January 1 through April 23, 2021. 2020 Impairment. In the first quarter of 2020, we evaluated five of our drilling rigs that had indicators of impairment. Based on our assumptions and analysis at that time, we determined that the carrying values of four of these rigs were impaired (we collectively refer to these four rigs as the 2020 Impaired Rigs). We estimated the fair values of the 2020 Impaired Rigs using an income approach, which utilized significant unobservable inputs, including management’s assumptions related to estimated dayrate revenue, rig utilization, estimated capital expenditures and repair costs, as well as estimated proceeds that may be received on ultimate disposition of each rig. Our 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. We recorded asset impairments aggregating $774.0 million for the six-month period ended June 30, 2020. See Note 9 “Drilling and Other Property and Equipment.” We evaluate our property and equipment for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If market fundamentals in the offshore oil and gas industry deteriorate further or a market recovery is further delayed, we may be required to recognize additional impairment charges in future periods.

Impairment of Assets

6 Months Ended

Jun. 30, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

5. Impairment of Assets

2021 Impairment. At June 30, 2021, we evaluated four drilling rigs with indicators of impairment. Based on our assumptions and analysis at that time, we determined that the undiscounted probability-weighted cash flow for each rig was in excess of its respective carrying value. As a result, we concluded that no impairment of these rigs had occurred. No asset impairments were recorded for the period from April 24 through June 30, 2021.

During the first quarter of 2021, we evaluated three of our drilling rigs with indicators of impairment. Based on our assumptions and analysis at that time, we determined that the carrying value of one of these rigs, for which we have concerns regarding future opportunities, was impaired (or the 2021 Impaired Rig). We estimated the fair value of the 2021 Impaired Rig using an income approach, whereby the fair value of the rig was estimated based on a calculation of the rig’s future net cash flows. These calculations utilized significant unobservable inputs, including management’s assumptions related to estimated dayrate revenue, rig utilization, estimated capital expenditures, repair and regulatory survey costs, as well as estimated proceeds that may be received on ultimate disposition of the rig. Our fair value estimate was representative of a Level 3 fair value measurement due to the significant level of estimation involved and the lack of transparency as to the inputs used. We recorded asset impairments aggregating $197.0 million for the period from January 1 through April 23, 2021.

2020 Impairment. In the first quarter of 2020, we evaluated five of our drilling rigs that had indicators of impairment. Based on our assumptions and analysis at that time, we determined that the carrying values of four of these rigs were impaired (we collectively refer to these four rigs as the 2020 Impaired Rigs).

We estimated the fair values of the 2020 Impaired Rigs using an income approach, which utilized significant unobservable inputs, including management’s assumptions related to estimated dayrate revenue, rig utilization, estimated capital expenditures and repair costs, as well as estimated proceeds that may be received on ultimate disposition of each rig. Our 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. We recorded asset impairments aggregating $774.0 million for the six-month period ended June 30, 2020.

See Note 9 “Drilling and Other Property and Equipment.”

We evaluate our property and equipment for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If market fundamentals in the offshore oil and gas industry deteriorate further or a market recovery is further delayed, we may be required to recognize additional impairment charges in future periods.