Unaudited Condensed Consolidated Financial Statements (Policies)	6 Months Ended
Jun. 30, 2018
Unaudited Condensed Consolidated Financial Statements [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In February 2018, the Financial Accounting Standards Board (the "FASB") issued Update 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects From Accumulated Other Comprehensive Income ("Update 2018-02"), which allows for a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. This update is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, with early adoption permitted. We adopted Update 2018-02 effective January 1, 2018. As a result, we reclassified a total of $800,000 in tax effects from AOCI to opening retained earnings. In August 2017, the FASB issued Update 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("Update 2017-12"), which will make more hedging strategies eligible for hedge accounting. It also amends presentation and disclosure requirements and changes how companies assess effectiveness. This update is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. We are currently evaluating the effect that Update 2017-12 will have on our consolidated financial statements and related disclosures. During 2016, the FASB issued Update 2016-02, Leases (Topic 842) ("Update 2016-02"), which requires an entity to recognize lease assets and lease liabilities on the balance sheet and to disclose key qualitative and quantitative information about the entity's leasing arrangements. This update is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. During our evaluation of Update 2016-02, we concluded that our drilling contracts contain a lease component. In January 2018, the FASB issued a Proposed Accounting Standard Update to provide targeted improvements to Update 2016-02, which (1) provides for a new transition method whereby entities may elect to adopt the Update using a prospective with cumulative catch-up approach and (2) provides lessors with a practical expedient to not separate non-lease components from the related lease components, by class of underlying asset. On March 28, 2018, the FASB held a meeting to approve certain additional amendments to Update 2016-02, including a revision to the practical expedient that would allow a lessor to account for the combined lease and non-lease components under Topic 606 (discussed below) when the non-lease component is the predominant element of the combined component. Depending on the criteria included in the final Update, this practical expedient may be available to us. As a result of the pending content of the final Update, we are not yet able to determine what, if any, impact our adoption will have on our revenue recognition patterns and related disclosures. With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting "right of use" assets ranging from approximately $60 million to $80 million. During 2014, the FASB issued Update 2014-09, Revenue from Contracts with Customers (Topic 606) ("Update 2014-09"), which requires entities to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Update 2014-09 is effective for annual and interim periods for fiscal years beginning after December 15, 2017. We adopted Update 2014-09 effective January 1, 2018, using the modified retrospective approach. Only customer contracts that were not completed as of the effective adoption date were evaluated under the transition guidance to determine if a cumulative catch-up adjustment to retained earnings was warranted. Revenues recognized in prior years for customer contracts that expired prior to the effective adoption date continue to be reported under the previous revenue recognition guidance. Our adoption of Update 2014-09 did not result in a cumulative effect on retained earnings and no adjustments were made to prior periods. While Update 2014-09 requires additional disclosure regarding revenues recognized from customer contracts, our adoption did not have a material impact on the recognition of current or prior period revenues as compared to previous guidance nor do we expect a material impact to our pattern of revenue recognition in future periods. See "Note 2 - Revenue from Contracts with Customers" for additional information.

New Accounting Pronouncements

In February 2018, the Financial Accounting Standards Board (the "FASB") issued Update 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects From Accumulated Other Comprehensive Income ("Update 2018-02"), which allows for a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. This update is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, with early adoption permitted. We adopted Update 2018-02 effective January 1, 2018. As a result, we reclassified a total of $800,000 in tax effects from AOCI to opening retained earnings.

In August 2017, the FASB issued Update 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities ("Update 2017-12"), which will make more hedging strategies eligible for hedge accounting. It also amends presentation and disclosure requirements and changes how companies assess effectiveness. This update is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. We are currently evaluating the effect that Update 2017-12 will have on our consolidated financial statements and related disclosures.

During 2016, the FASB issued Update 2016-02, Leases (Topic 842) ("Update 2016-02"), which requires an entity to recognize lease assets and lease liabilities on the balance sheet and to disclose key qualitative and quantitative information about the entity's leasing arrangements. This update is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted. During our evaluation of Update 2016-02, we concluded that our drilling contracts contain a lease component. In January 2018, the FASB issued a Proposed Accounting Standard Update to provide targeted improvements to Update 2016-02, which (1) provides for a new transition method whereby entities may elect to adopt the Update using a prospective with cumulative catch-up approach and (2) provides lessors with a practical expedient to not separate non-lease components from the related lease components, by class of underlying asset. On March 28, 2018, the FASB held a meeting to approve certain additional amendments to Update 2016-02, including a revision to the practical expedient that would allow a lessor to account for the combined lease and non-lease components under Topic 606 (discussed below) when the non-lease component is the predominant element of the combined component. Depending on the criteria included in the final Update, this practical expedient may be available to us. As a result of the pending content of the final Update, we are not yet able to determine what, if any, impact our adoption will have on our revenue recognition patterns and related disclosures. With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting "right of use" assets ranging from approximately $60 million to $80 million.

During 2014, the FASB issued Update 2014-09, Revenue from Contracts with Customers (Topic 606) ("Update 2014-09"), which requires entities to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. Update 2014-09 is effective for annual and interim periods for fiscal years beginning after December 15, 2017. We adopted Update 2014-09 effective January 1, 2018, using the modified retrospective approach. Only customer contracts that were not completed as of the effective adoption date were evaluated under the transition guidance to determine if a cumulative catch-up adjustment to retained earnings was warranted. Revenues recognized in prior years for customer contracts that expired prior to the effective adoption date continue to be reported under the previous revenue recognition guidance. Our adoption of Update 2014-09 did not result in a cumulative effect on retained earnings and no adjustments were made to prior periods. While Update 2014-09 requires additional disclosure regarding revenues recognized from customer contracts, our adoption did not have a material impact on the recognition of current or prior period revenues as compared to previous guidance nor do we expect a material impact to our pattern of revenue recognition in future periods. See "Note 2 - Revenue from Contracts with Customers" for additional information.