Commitments And Contingencies	6 Months Ended
Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES Litigation. In the ordinary course of business, we are subject to actions for damages alleging personal injury under the general maritime laws of the United States, including the Jones Act, for alleged negligence. We report actions for personal injury to our insurance carriers and believe that the settlement or disposition of those claims will not have a material adverse effect on our consolidated financial position, results of operations or cash flows. Various other actions and claims are pending against us, most of which are covered by insurance. Although we cannot predict the ultimate outcome of these matters, we believe that our ultimate liability, if any, that may result from these other actions and claims will not materially affect our results of operations, cash flows or financial position. Financial Instruments and Risk Concentration. In the normal course of business, we manage risks associated with foreign exchange rates and interest rates through a variety of strategies, including the use of hedging transactions. As a matter of policy, we do not use derivative instruments unless we have an underlying exposure. Other financial instruments that potentially subject us to concentrations of credit risk are principally cash and cash equivalents and accounts receivable. The carrying values of cash and cash equivalents approximate their fair values due to the short-term maturity of the underlying instruments. Accounts receivable are generated from a broad group of customers, primarily from within the energy industry, which is our major source of revenue. Due to their short-term nature, carrying values of our accounts receivable and accounts payable approximate fair market values. We estimated the aggregate fair market value of the Senior Notes to be $783 million as of June 30, 2018, based on quoted prices. Since the market for the Senior Notes is not an active market, the fair value of the Senior Notes is classified within Level 2 in the fair value hierarchy under U.S. GAAP (inputs other than quoted prices in active markets for similar assets and liabilities that are observable or can be corroborated by observable market data for substantially the full terms for the assets or liabilities). We have two interest rate swaps in place on a total of $200 million of the 2024 Senior Notes for the period to November 2024. The agreements swap the fixed interest rate of 4.650% on $100 million of the 2024 Senior Notes to the floating rate of one month LIBOR plus 2.426% and on another $100 million to one month LIBOR plus 2.823%. We estimate the combined fair value of the interest rate swaps to be a net liability of $9.4 million as of June 30, 2018, which is included on our balance sheet in our Other Long-term Liabilities. These values were arrived at based on a discounted cash flow model using Level 2 inputs. Since the second quarter of 2015, the exchange rate for the Angolan kwanza relative to the U.S. dollar generally has been declining, although the exchange rate was relatively stable during 2017. As our functional currency in Angola is the U.S. dollar, we recorded foreign currency transaction losses related to the kwanza of $4.8 million and $12.4 million in the three- and six-month periods ended June 30, 2018, respectively, as a component of Other income (expense), net in our Consolidated Statements of Operations for those respective periods. Our foreign currency transaction gains or losses related primarily to the remeasurement of our Angolan kwanza cash balances to U.S. dollars. Conversion of cash balances from kwanza to U.S. dollars is controlled by the central bank in Angola, and the central bank has slowed this process since mid-2015, causing our kwanza cash balances to subsequently increase. As of June 30, 2018 and December 31, 2017, we had the equivalent of approximately $12 million and $27 million of kwanza cash balances, respectively, in Angola reflected on our balance sheet. To mitigate our currency exposure risk in Angola, we have used kwanza to purchase equivalent Angolan central bank (Banco Nacional de Angola) bonds. The bonds are denominated as U.S. dollar equivalents, so that, upon payment of semi-annual interest and principal upon maturity, payment is made in kwanza, equivalent to the respective U.S. dollars at the then-current exchange rate. Our intention was to hold the bonds to maturity, and to reinvest funds from maturing bonds in similar long-term assets. We previously believed the chance of selling the bonds before maturity and repatriating cash out of Angola was remote. However, in the second quarter of 2018, $10 million of bonds matured which we reinvested in similar long-term assets. Additionally, we sold $23 million of bonds prior to their maturity date. As a result, we have changed our accounting for these bonds from held-to-maturity securities to available-for-sale securities, as we intend to sell the bonds if we are able to repatriate the proceeds. As of June 30, 2018, we have classified $31 million of bonds due to mature in the next twelve months as Other current assets and $15 million of bonds due to mature after twelve months as Other non-current assets on our Consolidated Balance Sheet, with $5 million maturing in 2020 and $10 million maturing in 2023. During the second quarter of 2018, we were able to repatriate $31 million of cash from Angola. We estimated the fair market value of the Angolan bonds to be approximately $46 million as of June 30, 2018 using quoted prices. Since the market for the Angolan bonds is not an active market, the fair value of the Angolan bonds is classified within Level 2 in the fair value hierarchy under U.S. GAAP. As of June 30, 2018, we have not recorded the difference between the fair market value and carrying amount of the outstanding bonds through the Consolidated Statement of Comprehensive Income (Loss) due to the insignificance of the difference between the fair market value and the carrying amount of the bonds.

COMMITMENTS AND CONTINGENCIES

Litigation. In the ordinary course of business, we are subject to actions for damages alleging personal injury under the general maritime laws of the United States, including the Jones Act, for alleged negligence. We report actions for personal injury to our insurance carriers and believe that the settlement or disposition of those claims will not have a material adverse effect on our consolidated financial position, results of operations or cash flows.

Various other actions and claims are pending against us, most of which are covered by insurance. Although we cannot predict the ultimate outcome of these matters, we believe that our ultimate liability, if any, that may result from these other actions and claims will not materially affect our results of operations, cash flows or financial position.

Financial Instruments and Risk Concentration. In the normal course of business, we manage risks associated with foreign exchange rates and interest rates through a variety of strategies, including the use of hedging transactions. As a matter of policy, we do not use derivative instruments unless we have an underlying exposure. Other financial instruments that potentially subject us to concentrations of credit risk are principally cash and cash equivalents and accounts receivable.

The carrying values of cash and cash equivalents approximate their fair values due to the short-term maturity of the underlying instruments. Accounts receivable are generated from a broad group of customers, primarily from within the energy industry, which is our major source of revenue. Due to their short-term nature, carrying values of our accounts receivable and accounts payable approximate fair market values.

We estimated the aggregate fair market value of the Senior Notes to be $783 million as of June 30, 2018, based on quoted prices. Since the market for the Senior Notes is not an active market, the fair value of the Senior Notes is classified within Level 2 in the fair value hierarchy under U.S. GAAP (inputs other than quoted prices in active markets for similar assets and liabilities that are observable or can be corroborated by observable market data for substantially the full terms for the assets or liabilities).

We have two interest rate swaps in place on a total of $200 million of the 2024 Senior Notes for the period to November 2024. The agreements swap the fixed interest rate of 4.650% on $100 million of the 2024 Senior Notes to the floating rate of one month LIBOR plus 2.426% and on another $100 million to one month LIBOR plus 2.823%. We estimate the combined fair value of the interest rate swaps to be a net liability of $9.4 million as of June 30, 2018, which is included on our balance sheet in our Other Long-term Liabilities. These values were arrived at based on a discounted cash flow model using Level 2 inputs.

Since the second quarter of 2015, the exchange rate for the Angolan kwanza relative to the U.S. dollar generally has been declining, although the exchange rate was relatively stable during 2017. As our functional currency in Angola is the U.S. dollar, we recorded foreign currency transaction losses related to the kwanza of $4.8 million and $12.4 million in the three- and six-month periods ended June 30, 2018, respectively, as a component of Other income (expense), net in our Consolidated Statements of Operations for those respective periods. Our foreign currency transaction gains or losses related primarily to the remeasurement of our Angolan kwanza cash balances to U.S. dollars. Conversion of cash balances from kwanza to U.S. dollars is controlled by the central bank in Angola, and the central bank has slowed this process since mid-2015, causing our kwanza cash balances to subsequently increase. As of June 30, 2018 and December 31, 2017, we had the equivalent of approximately $12 million and $27 million of kwanza cash balances, respectively, in Angola reflected on our balance sheet.

To mitigate our currency exposure risk in Angola, we have used kwanza to purchase equivalent Angolan central bank (Banco Nacional de Angola) bonds. The bonds are denominated as U.S. dollar equivalents, so that, upon payment of semi-annual interest and principal upon maturity, payment is made in kwanza, equivalent to the respective U.S. dollars at the then-current exchange rate. Our intention was to hold the bonds to maturity, and to reinvest funds from maturing bonds in similar long-term assets. We previously believed the chance of selling the bonds before maturity and repatriating cash out of Angola was remote. However, in the second quarter of 2018, $10 million of bonds matured which we reinvested in similar long-term assets. Additionally, we sold $23 million of bonds prior to their maturity date. As a result, we have changed our accounting for these bonds from held-to-maturity securities to available-for-sale securities, as we intend to sell the bonds if we are able to repatriate the proceeds. As of June 30, 2018, we have classified $31 million of bonds due to mature in the next twelve months as Other current assets and $15 million of bonds due to mature after twelve months as Other non-current assets on our Consolidated Balance Sheet, with $5 million maturing in 2020 and $10 million maturing in 2023. During the second quarter of 2018, we were able to repatriate $31 million of cash from Angola.

We estimated the fair market value of the Angolan bonds to be approximately $46 million as of June 30, 2018 using quoted prices. Since the market for the Angolan bonds is not an active market, the fair value of the Angolan bonds is classified within Level 2 in the fair value hierarchy under U.S. GAAP. As of June 30, 2018, we have not recorded the difference between the fair market value and carrying amount of the outstanding bonds through the Consolidated Statement of Comprehensive Income (Loss) due to the insignificance of the difference between the fair market value and the carrying amount of the bonds.