Unaudited Interim Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Consolidated Statements Of Cash Flows (Abstract)
Net Cash Provided by Operating Activities	$ 160,922	$ 367,529
Cash Flows Used in Investing Activities:
Advances for drilling units under construction and related costs	(35,552)	(17,440)
Drilling units, machinery, equipment and other improvements/ upgrades	(5,772)	(7,147)
Sale of fixed assets	50	190
Net Cash Used in Investing Activities	(41,274)	(24,397)
Cash Flows Used in Financing Activities:
Principal payments and prepayments of long-term debt and senior notes	(181,886)	(96,674)
Reorganization expenses	(227)	(41,043)
Net Cash Used in Financing Activities	(182,113)	(137,717)
Effect on exchange rate changes on cash and cash equivalents and restricted cash	(1,390)	0
Net increase/ (decrease) in cash and cash equivalents and restricted cash	(63,855)	205,415
Cash and cash equivalents and restricted cash at beginning of period	783,081	772,966
Cash and cash equivalents and restricted cash at end of period	719,226	978,381
Cash paid during the period for:
Interest, net of amount capitalized	17,324	48,766
Reorganization expenses paid	$ 227	$ 41,043

This element represents advances paid and capitalized expenses for the construction or acquisition of drilling units.

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This element represents payments for acquisition and other improvements of drilling units and other machinery and equipment.

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Amount of expense paid in relation to the reorganization of the company.

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Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of cash paid for interest, excluding capitalized interest, classified as operating activity. Includes, but is not limited to, payment to settle zero-coupon bond for accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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The cash outflow for cost incurred in the modification of term of existing debt agreement in order for the entity to achieve some advantage.

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The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

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