Unaudited Condensed Consolidated Financial Statements (Policies)	9 Months Ended
Sep. 30, 2017
Unaudited Condensed Consolidated Financial Statements [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In August 2017, the Financial Accounting Standards Board (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. In October 2016, the FASB issued Accounting Standards Update 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“Update 2016-16”), which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transaction occurs as opposed to deferring tax consequences and amortizing them into future periods. We adopted Update 2016-16 on a modified retrospective basis effective January 1, 2017. As a result of modified retrospective application, we reduced prepaid taxes on intercompany transfers of property and related deferred tax liabilities resulting in the recognition of a cumulative-effect reduction in retained earnings of $14.1 million on our condensed consolidated balance sheet as of January 1, 2017. We do not expect a material impact to our 2017 operating results as a result of the adoption of Update 2016-16. In March 2016, the FASB issued Accounting Standards Update 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("Update 2016-09"), which simplifies several aspects of accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted Update 2016-09 effective January 1, 2017. Our adoption of Update 2016-09 did not result in any cumulative effect on retained earnings and no adjustments have been made to prior periods. The new standard will cause volatility in our effective tax rates primarily due to the new requirement to recognize additional tax benefits or expenses in earnings related to the vesting or settlement of employee share-based awards, rather than in additional paid-in capital, during the period in which they occur. Furthermore, forfeitures are now recorded as they occur as opposed to estimating an allowance for future forfeitures. During 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers (Topic 606) ("Update 2014-09"), which requires an entity 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. Subsequent to the issuance of Update 2014-09, the FASB issued several additional Accounting Standards Updates to clarify implementation guidance, provide narrow-scope improvements and provide additional disclosure guidance. Update 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP and may be adopted using a retrospective, modified retrospective or prospective with a cumulative catch-up approach. Due to the significant interaction between Update 2014-09 and Accounting Standards Update 2016-02, Leases (Topic 842): Amendments to the FASB Accounting Standards Codification ("Update 2016-02"), we expect to adopt Update 2014-09 and Update 2016-02 concurrently with an effective date of January 1, 2018. We expect to apply the modified retrospective approach to our adoption. We are currently evaluating the effect that Update 2014-09 and Update 2016-02 will have on our consolidated financial statements and related disclosures. In February 2016, the FASB issued 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. A modified retrospective approach is required. During our evaluation of Update 2016-02, we have concluded that our drilling contracts contain a lease component, and upon adoption, we will be required to separately recognize revenues associated with the lease of our drilling rigs and the provision of contract drilling services. Due to the significant interaction between Update 2016-02 and Update 2014-09, we expect to adopt both updates concurrently with an effective date of January 1, 2018. Adoption will result in increased disclosure of the nature of our leasing arrangements and may result in variability in our revenue recognition patterns relative to current U.S. GAAP based on the provisions in each of our drilling contracts. With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting "right of use" assets ranging from approximately $70 million to $90 million. We are currently evaluating the other impacts that Update 2016-02 and Update 2014-09 will have on our consolidated financial statements and related disclosures.

New Accounting Pronouncements

In August 2017, the Financial Accounting Standards Board (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.

In October 2016, the FASB issued Accounting Standards Update 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“Update 2016-16”), which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transaction occurs as opposed to deferring tax consequences and amortizing them into future periods. We adopted Update 2016-16 on a modified retrospective basis effective January 1, 2017. As a result of modified retrospective application, we reduced prepaid taxes on intercompany transfers of property and related deferred tax liabilities resulting in the recognition of a cumulative-effect reduction in retained earnings of $14.1 million on our condensed consolidated balance sheet as of January 1, 2017. We do not expect a material impact to our 2017 operating results as a result of the adoption of Update 2016-16.

In March 2016, the FASB issued Accounting Standards Update 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting ("Update 2016-09"), which simplifies several aspects of accounting for share-based payment transactions including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted Update 2016-09 effective January 1, 2017. Our adoption of Update 2016-09 did not result in any cumulative effect on retained earnings and no adjustments have been made to prior periods. The new standard will cause volatility in our effective tax rates primarily due to the new requirement to recognize additional tax benefits or expenses in earnings related to the vesting or settlement of employee share-based awards, rather than in additional paid-in capital, during the period in which they occur. Furthermore, forfeitures are now recorded as they occur as opposed to estimating an allowance for future forfeitures.

During 2014, the FASB issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers (Topic 606) ("Update 2014-09"), which requires an entity 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. Subsequent to the issuance of Update 2014-09, the FASB issued several additional Accounting Standards Updates to clarify implementation guidance, provide narrow-scope improvements and provide additional disclosure guidance. Update 2014-09 will replace most existing revenue recognition guidance in U.S. GAAP and may be adopted using a retrospective, modified retrospective or prospective with a cumulative catch-up approach. Due to the significant interaction between Update 2014-09 and Accounting Standards Update 2016-02, Leases (Topic 842): Amendments to the FASB Accounting Standards Codification ("Update 2016-02"), we expect to adopt Update 2014-09 and Update 2016-02 concurrently with an effective date of January 1, 2018. We expect to apply the modified retrospective approach to our adoption. We are currently evaluating the effect that Update 2014-09 and Update 2016-02 will have on our consolidated financial statements and related disclosures.

In February 2016, the FASB issued 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. A modified retrospective approach is required. During our evaluation of Update 2016-02, we have concluded that our drilling contracts contain a lease component, and upon adoption, we will be required to separately recognize revenues associated with the lease of our drilling rigs and the provision of contract drilling services. Due to the significant interaction between Update 2016-02 and Update 2014-09, we expect to adopt both updates concurrently with an effective date of January 1, 2018. Adoption will result in increased disclosure of the nature of our leasing arrangements and may result in variability in our revenue recognition patterns relative to current U.S. GAAP based on the provisions in each of our drilling contracts. With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting "right of use" assets ranging from approximately $70 million to $90 million. We are currently evaluating the other impacts that Update 2016-02 and Update 2014-09 will have on our consolidated financial statements and related disclosures.