Valaris Limited (VAL) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 22, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Entity Registrant Name	Ensco plc
Entity Central Index Key	314,808
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 3,149,586,000
Entity Emerging Growth Company	false
Entity Common Shares, Shares Outstanding		437,071,204
Entity Small Business	false
Entity Shell Company	false

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
OPERATING REVENUES	$ 1,705.4	$ 1,843	$ 2,776.4
OPERATING EXPENSES
Contract drilling (exclusive of depreciation)	1,319.4	1,189.5	1,301
Loss on impairment	40.3	182.9	0
Depreciation	478.9	444.8	445.3
General and administrative	102.7	157.8	100.8
Total operating expenses	1,941.3	1,975	1,847.1
OPERATING INCOME (LOSS)	(235.9)	(132)	929.3
OTHER INCOME (EXPENSE)
Interest income	14.5	25.8	13.8
Interest expense, net	(282.7)	(224.2)	(228.8)
Other, net	(34.8)	134.4	283.2
Other income (expense), net	(303)	(64)	68.2
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(538.9)	(196)	997.5
PROVISION FOR INCOME TAXES
Current income tax expense	33	54.2	79.8
Deferred income tax expense (benefit)	56.6	55	28.7
Total provision for income taxes	89.6	109.2	108.5
INCOME (LOSS) FROM CONTINUING OPERATIONS	(628.5)	(305.2)	889
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET	(8.1)	1	8.1
NET INCOME (LOSS)	(636.6)	(304.2)	897.1
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(3.1)	0.5	(6.9)
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO	$ (639.7)	$ (303.7)	$ 890.2
EARNINGS (LOSS) PER SHARE - BASIC AND DILUTED
Continuing operations	$ (1.45)	$ (0.91)	$ 3.10
Discontinued operations	(0.02)	0	0.03
Total earnings per share - basic	$ (1.47)	$ (0.91)	$ 3.13
WEIGHTED-AVERAGE SHARES OUTSTANDING
Basic and Diluted	434.1	332.5	279.1

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS)	$ (203.1)	$ (142.9)	$ (150.1)	$ (140.5)	$ (207.1)	$ (28.2)	$ (44.3)	$ (24.6)	$ (636.6)	$ (304.2)	$ 897.1
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									(9.7)	8.5	(5.4)
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									(1)	0.4	12.4
Other									(0.5)	0.7	(0.5)
NET OTHER COMPREHENSIVE INCOME (LOSS)									(11.2)	9.6	6.5
COMPREHENSIVE INCOME (LOSS)									(647.8)	(294.6)	903.6
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									(3.1)	0.5	(6.9)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									$ (650.9)	$ (294.1)	$ 896.7

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 275.1	$ 445.4
Short-term Investments	329	440
Accounts receivable, net	344.7	345.4
Other	360.9	381.2
Total current assets	1,309.7	1,612
PROPERTY AND EQUIPMENT, AT COST	15,517	15,332.1
Less accumulated depreciation	2,900.8	2,458.4
Property and equipment, net	12,616.2	12,873.7
OTHER ASSETS, NET	97.8	140.2
TOTAL ASSETS	14,023.7	14,625.9
CURRENT LIABILITIES
Accounts payable - trade	210.5	432.6
Accrued liabilities and other	318	325.9
Total current liabilities	528.5	758.5
LONG-TERM DEBT	5,010.4	4,750.7
OTHER LIABILITIES	396	386.7
COMMITMENTS AND CONTINGENCIES
ENSCO SHAREHOLDERS' EQUITY
Additional paid-in capital	7,225	7,195
Retained earnings	874.2	1,532.7
Accumulated other comprehensive income	18.2	28.6
Treasury shares, at cost, 23.6 million and 11.1 million shares as of December 31, 2018 and 2017	(72.2)	(69)
Total Ensco shareholders' equity	8,091.4	8,732.1
NONCONTROLLING INTERESTS	(2.6)	(2.1)
Total equity	8,088.8	8,730
Total liabilities and shareholders' equity	14,023.7	14,625.9
Class A Ordinary Shares, U.S. [Member]
ENSCO SHAREHOLDERS' EQUITY
Common shares, value	46.1	44.7
Common Class B, Par Value In GBP [Member]
ENSCO SHAREHOLDERS' EQUITY
Common shares, value	$ 0.1	$ 0.1

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical)	Dec. 31, 2018£ / sharesshares	Dec. 31, 2018$ / sharesshares	Dec. 31, 2017£ / sharesshares	Dec. 31, 2017$ / sharesshares
Treasury shares, shares held	23,600,000	23,600,000	11,100,000	11,100,000
Class A Ordinary Shares, U.S. [Member]
Common shares, par value | $ / shares		$ 0.10		$ 0.10
Common shares, shares issued	460,700,000	460,700,000	447,000,000	447,000,000
Common Class B, Par Value In GBP [Member]
Common shares, par value | £ / shares	£ 1		£ 1
Common shares, shares issued	50,000	50,000	50,000	50,000

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES
Net income (loss)	$ (636.6)	$ (304.2)	$ 897.1
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities of continuing operations:
Depreciation expense	478.9	444.8	445.3
Deferred income tax expense (benefit)	56.6	55	28.7
Share-based compensation expense	41.6	41.2	39.6
Loss on impairment	40.3	182.9	0
Amortization	(40.2)	(61.6)	(139.7)
(Gain) loss on debt extinguishment	19	2.6	(287.8)
Discontinued operations, net	8.1	(1)	(8.1)
Bargain purchase gain	(1.8)	(140.2)	0
Other	(3.6)	(25.5)	(38.3)
Changes in operating assets and liabilities, net of acquisition	(18)	65.4	140.6
Net cash provided by operating activities of continuing operations	(55.7)	259.4	1,077.4
INVESTING ACTIVITIES
Maturities of short-term investments	1,030	2,042.5	2,212
Purchases of short-term investments	(919)	(1,040)	(2,474.6)
Additions to property and equipment	(426.7)	(536.7)	(322.2)
Net proceeds from disposition of assets	11	2.8	9.8
Acquisition of Atwood, net of cash acquired	0	(871.6)	0
Net cash used in investing activities of continuing operations	(304.7)	(403)	(575)
FINANCING ACTIVITIES
Proceeds from issuance of senior notes	1,000	0	849.5
Reduction of long-term borrowings	(771.2)	(537)	(863.9)
Cash dividends paid	(17.9)	(13.8)	(11.6)
Debt financing costs	(17)	(12)	(23.4)
Proceeds from equity issuance	0	0	585.5
Other	(5.7)	(7.7)	(7.1)
Net cash provided by (used in) financing activities	188.2	(570.5)	529
Net cash provided by (used in) discontinued operations	2.5	(0.8)	8.4
Effect of exchange rate changes on cash and cash equivalents	(0.6)	0.6	(1.4)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(170.3)	(714.3)	1,038.4
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR	445.4	1,159.7	121.3
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 275.1	$ 445.4	$ 1,159.7

Description Of The Business And

Description Of The Business And Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Description Of The Business And Summary Of Significant Accounting Policies	DESCRIPTION OF THE BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Business We are one of the leading providers of offshore contract drilling services to the international oil and gas industry. We own and operate an offshore drilling rig fleet of 56 rigs spanning most of the strategic markets around the globe. We also have three rigs under construction. Inclusive of our rigs under construction, our fleet includes 12 drillships, 9 dynamically positioned semisubmersible rigs, three moored semisubmersible rigs and 35 jackup rigs. We operate the world's largest fleet amongst competitive rigs, including one of the newest ultra-deepwater fleets in the industry and a leading premium jackup fleet. Our customers include many of the leading national and international oil companies, in addition to many independent operators. We are among the most geographically diverse offshore drilling companies, with current operations spanning 14 countries on six continents. The markets in which we operate include the Gulf of Mexico, Brazil, the Mediterranean, the North Sea, the Middle East, West Africa, Australia and Southeast Asia. We provide drilling services on a day rate contract basis. Under day rate contracts, we provide an integrated service that includes the provision of a drilling rig and rig crews for which we receive a daily rate that may vary between the full rate and zero rate throughout the duration of the contractual term, depending on the operations of the rig. We also may receive lump-sum fees or similar compensation for the mobilization, demobilization and capital upgrades of our rigs. Our customers bear substantially all of the costs of constructing the well and supporting drilling operations, as well as the economic risk relative to the success of the well. Proposed Rowan Transaction On October 7, 2018, Ensco plc and Rowan Companies plc ("Rowan") entered into an agreement that provides for the combination of the two companies (as amended the "Transaction Agreement"). Ensco has agreed to acquire the entire issued and to be issued share capital of Rowan in an all-stock transaction (the " Rowan Transaction") by way of a scheme of arrangement to be undertaken by Rowan under Part 26 of the UK Companies Act 2006. On January 29, 2019, the Transaction Agreement was amended to increase the exchange ratio in connection with the Rowan Transaction from 2.215 to 2.750 . Subject to the terms and conditions of the Transaction Agreement, each Class A ordinary share of Rowan will be converted into the right to receive 2.750 Class A ordinary shares of Ensco plc. We estimate the total consideration to be delivered in the Rowan Transaction to be approximately $1.5 billion , consisting of approximately 351.3 million of our shares based on the closing price of $4.41 on February 22, 2019 . The value of the Rowan Transaction consideration will fluctuate until the closing date based on changes in the price of our shares and the number of Rowan ordinary shares outstanding. The completion of the Rowan Transaction is subject to various closing conditions, including, among others, (i) the sanction of the Rowan Transaction by the High Court of Justice of England and Wales, (ii) the receipt of certain required regulatory approvals or lapse of certain review periods with respect thereto, including in the Kingdom of Saudi Arabia, (iii) the absence of legal restraints prohibiting or restraining the Rowan Transaction and (iv) the absence of any law or order reasonably expected to result in the dissolution of the Saudi Aramco Offshore Drilling Company, Rowan’s joint venture with Saudi Aramco (the “ARO JV”), or the sale, disposition, forfeiture or nationalization of Rowan’s interest in the ARO JV. Shareholders of Rowan and Ensco approved the Rowan Transaction on February 21, 2019. The Rowan Transaction is expected to close during the first half of 2019, subject to satisfaction of all conditions to closing. Upon closing of the Rowan Transaction, we intend to complete a reverse split of our ordinary shares under which every four existing Ensco ordinary shares will be consolidated into one Ensco ordinary share. Atwood Merger On October 6, 2017 (the "Merger Date"), we completed a merger transaction (the "Atwood Merger") with Atwood Oceanics, Inc. ("Atwood") and Echo Merger Sub, LLC, a wholly-owned subsidiary of Ensco plc. Pursuant to the merger agreement, Echo Merger Sub, LLC, merged with and into Atwood, with Atwood as the surviving entity and an indirect, wholly-owned subsidiary of Ensco plc. Total consideration delivered in the Atwood Merger consisted of 132.2 million of our Class A ordinary shares and $11.1 million of cash in settlement of certain share-based payment awards. The total aggregate value of consideration transferred was $781.8 million . Additionally, upon closing of the Atwood Merger, we utilized cash acquired of $445.4 million and cash on hand to extinguish Atwood's revolving credit facility, outstanding senior notes and accrued interest totaling $1.3 billion . The estimated fair values assigned to assets acquired net of liabilities assumed exceeded the consideration transferred, resulting in a bargain purchase gain of $140.2 million that was recognized during the fourth quarter of 2017. During 2018, we recognized measurement period adjustments as we completed our fair value assessments resulting in additional bargain purchase gain of $1.8 million . Basis of Presentation—U.K. Companies Act 2006 Section 435 Statement The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP, which the Board of Directors consider to be the most meaningful presentation of our results of operations and financial position. The accompanying consolidated financial statements do not constitute U.K. statutory accounts for the year ended December 31, 2018 and 2017 as required to be prepared under the U.K. Companies Act 2006. The U.K. statutory accounts are prepared in accordance with Financial Reporting Standard 102, the financial reporting standard applicable in the U.K. and Republic of Ireland (“FRS 102”). The auditor has reported on the U.K. statutory accounts for the year ended December 31, 2017; their report was (i) unqualified, (ii) did not include a reference to any matters to which the auditor drew attention by way of emphasis without qualifying their report and (iii) did not contain a statement under section 498 (2) or (3) of the U.K. Companies Act 2006. The U.K. statutory accounts for the year ended December 31, 2018 have yet to be finalized and will be delivered to the U.K. registrar of companies during 2019. Principles of Consolidation The accompanying consolidated financial statements include the accounts of Ensco plc, those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. All intercompany accounts and transactions have been eliminated. Certain previously reported amounts have been reclassified to conform to the current year presentation. Pervasiveness of Estimates The preparation of financial statements in conformity with U.S. GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the related revenues and expenses and disclosures of gain and loss contingencies as of the date of the financial statements. Actual results could differ from those estimates. Foreign Currency Remeasurement and Translation Our functional currency is the U.S. dollar. As is customary in the oil and gas industry, a majority of our revenues and expenses are denominated in U.S. dollars; however, a portion of the revenues earned and expenses incurred by certain of our subsidiaries are denominated in currencies other than the U.S. dollar. These transactions are remeasured in U.S. dollars based on a combination of both current and historical exchange rates. Most transaction gains and losses, including certain gains and losses on our derivative instruments, are included in other, net, in our consolidated statement of operations. Certain gains and losses from the translation of foreign currency balances of our non-U.S. dollar functional currency subsidiaries are included in accumulated other comprehensive income on our consolidated balance sheet. Net foreign currency exchange losses, inclusive of offsetting fair value derivatives, were $17.2 million , $5.1 million and $6.0 million , and were included in other, net, in our consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 , respectively. Cash Equivalents and Short-Term Investments Highly liquid investments with maturities of three months or less at the date of purchase are considered cash equivalents. Highly liquid investments with maturities of greater than three months but less than one year at the date of purchase are classified as short-term investments. Short-term investments consisted of time deposits with initial maturities in excess of three months but less than one year and totaled $329.0 million and $440.0 million as of December 31, 2018 and 2017 , respectively. Cash flows from purchases and maturities of short-term investments were classified as investing activities in our consolidated statements of cash flows for the years ended December 31, 2018, 2017 and 2016 . To mitigate our credit risk, our investments in time deposits are diversified across multiple, high-quality financial institutions. Property and Equipment All costs incurred in connection with the acquisition, construction, major enhancement and improvement of assets are capitalized, including allocations of interest incurred during periods that our drilling rigs are under construction or undergoing major enhancements and improvements. Costs incurred to place an asset into service are capitalized, including costs related to the initial mobilization of a newbuild drilling rig. Repair and maintenance costs are charged to contract drilling expense in the period in which they are incurred. Upon the sale or retirement of assets, the related cost and accumulated depreciation are removed from the balance sheet, and the resulting gain or loss is included in contract drilling expense, unless reclassified to discontinued operations. Our property and equipment is depreciated on a straight-line basis, after allowing for salvage values, over the estimated useful lives of our assets. Drilling rigs and related equipment are depreciated over estimated useful lives ranging from four to 35 years. Buildings and improvements are depreciated over estimated useful lives ranging from seven to 30 years. Other equipment, including computer and communications hardware and software costs, is depreciated over estimated useful lives ranging from three to six years. We evaluate the carrying value of our property and equipment for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. For property and equipment used in our operations, recoverability generally is determined by comparing the carrying value of an asset to the expected undiscounted future cash flows of the asset. If the carrying value of an asset is not recoverable, the amount of impairment loss is measured as the difference between the carrying value of the asset and its estimated fair value. Property and equipment held-for-sale is recorded at the lower of net book value or fair value less cost to sell. We recorded pre-tax, non-cash impairment losses related to long-lived assets of $40.3 million and $182.9 million during 2018 and 2017, respectively. See "Note 5 - Property and Equipment" for additional information on our impairment charges. If the global economy deteriorates and/or our expectations relative to future offshore drilling industry conditions decline, it is reasonably possible that additional impairment charges may occur with respect to specific individual rigs, groups of rigs, such as a specific type of drilling rig, or rigs in a certain geographic location. Operating Revenues and Expenses See "Note 2 - Revenue from Contracts with Customers" for information on our accounting policies for revenue recognition and certain operating costs that are deferred and amortized over future periods, which reflects our revenue recognition policies subsequent to our adoption of ASC Topic 606, Revenue from Contracts with Customers , effective January 1, 2018. Prior to our adoption of ASC Topic 606, we recognized revenue in accordance with prior guidance under ASC Topic 605. With the exception of a change in our policy to recognize demobilization revenue over the related contract term, if certain conditions are met, our revenue recognition policies are substantively unchanged as a result of our adoption of ASC Topic 606. Derivative Instruments We use derivatives to reduce our exposure to various market risks, primarily foreign currency exchange rate risk. See "Note 7 - Derivative Instruments" for additional information on how and why we use derivatives. All derivatives are recorded on our consolidated balance sheet at fair value. Derivatives subject to legally enforceable master netting agreements are not offset on our consolidated balance sheet. Accounting for the gains and losses resulting from changes in the fair value of derivatives depends on the use of the derivative and whether it qualifies for hedge accounting. Derivatives qualify for hedge accounting when they are formally designated as hedges and are effective in reducing the risk exposure that they are designated to hedge. Changes in the fair value of derivatives that are designated as hedges of the variability in expected future cash flows associated with existing recognized assets or liabilities or forecasted transactions ("cash flow hedges") are recorded in accumulated other comprehensive income ("AOCI"). Amounts recorded in AOCI associated with cash flow hedges are subsequently reclassified into contract drilling, depreciation or interest expense as earnings are affected by the underlying hedged forecasted transactions. Gains and losses on a cash flow hedge, or a portion of a cash flow hedge, that no longer qualifies as effective due to an unanticipated change in the forecasted transaction are recognized currently in earnings and included in other, net, in our consolidated statement of operations based on the change in the fair value of the derivative. When a forecasted transaction becomes probable of not occurring, gains and losses on the derivative previously recorded in AOCI are reclassified currently into earnings and included in other, net, in our consolidated statement of operations. We occasionally enter into derivatives that hedge the fair value of recognized assets or liabilities, but do not designate such derivatives as hedges or the derivatives otherwise do not qualify for hedge accounting. In these situations, a natural hedging relationship generally exists where changes in the fair value of the derivatives offset changes in the fair value of the underlying hedged items. Changes in the fair value of these derivatives are recognized currently in earnings in other, net, in our consolidated statement of operations. Derivatives with asset fair values are reported in other current assets or other assets, net, on our consolidated balance sheet depending on maturity date. Derivatives with liability fair values are reported in accrued liabilities and other, or other liabilities on our consolidated balance sheet depending on maturity date. Income Taxes We conduct operations and earn income in numerous countries. Current income taxes are recognized for the amount of taxes payable or refundable based on the laws and income tax rates in the taxing jurisdictions in which operations are conducted and income is earned. Deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the enacted tax rates in effect at year-end. A valuation allowance for deferred tax assets is recorded when it is more-likely-than-not that the benefit from the deferred tax asset will not be realized. We do not offset deferred tax assets and deferred tax liabilities attributable to different tax paying jurisdictions. We operate in certain jurisdictions where tax laws relating to the offshore drilling industry are not well developed and change frequently. Furthermore, we may enter into transactions with affiliates or employ other tax planning strategies that generally are subject to complex tax regulations. As a result of the foregoing, the tax liabilities and assets we recognize in our financial statements may differ from the tax positions taken, or expected to be taken, in our tax returns. Our tax positions are evaluated for recognition using a more-likely-than-not threshold, and those tax positions requiring recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon effective settlement with a taxing authority that has full knowledge of all relevant information. Interest and penalties relating to income taxes are included in current income tax expense in our consolidated statement of operations. Our drilling rigs frequently move from one taxing jurisdiction to another based on where they are contracted to perform drilling services. The movement of drilling rigs among taxing jurisdictions may involve a transfer of drilling rig ownership among our subsidiaries through an intercompany rig sale. The pre-tax profit resulting from an intercompany rig sale is eliminated from our consolidated financial statements, and the carrying value of a rig sold in an intercompany transaction remains at historical net depreciated cost prior to the transaction. Our consolidated financial statements do not reflect the asset disposition transaction of the selling subsidiary or the asset acquisition transaction of the acquiring subsidiary. Prior to our adoption of Accounting Standards Update 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“Update 2016-16”) on January 1, 2017, income taxes resulting from an intercompany rig sale, as well as the tax effect of any reversing temporary differences resulting from the sale, were deferred and amortized on a straight-line basis over the remaining useful life of the rig. Subsequent to our adoption of Update 2016-16, the income tax effects resulting from intercompany rig sales are recognized in earnings in the period in which the sale occurs. In some instances, we may determine that certain temporary differences will not result in a taxable or deductible amount in future years, as it is more-likely-than-not we will commence operations and depart from a given taxing jurisdiction without such temporary differences being recovered or settled. Under these circumstances, no future tax consequences are expected and no deferred taxes are recognized in connection with such operations. We evaluate these determinations on a periodic basis and, in the event our expectations relative to future tax consequences change, the applicable deferred taxes are recognized or derecognized. We do not provide deferred taxes on the undistributed earnings of certain subsidiaries because our policy and intention is to reinvest such earnings indefinitely. Should we make a distribution from these subsidiaries in the form of dividends or otherwise, we may be subject to additional income taxes. The U.S. Tax Cuts and Jobs Act (“U.S. tax reform”) was enacted on December 22, 2017 and introduced significant changes to U.S. income tax law, including a reduction in the statutory income tax rate from 35% to 21% effective January 1, 2018, a one-time transition tax on deemed repatriation of deferred foreign income, a base erosion anti-abuse tax that effectively imposes a minimum tax on certain payments to non-U.S. affiliates, new and revised rules relating to the current taxation of certain income of foreign subsidiaries and revised rules associated with limitations on the deduction of interest. See "Note 10 - Income Taxes" for additional information. Share-Based Compensation We sponsor share-based compensation plans that provide equity compensation to our key employees, officers and non-employee directors. Our Long-Term Incentive Plan (the “2018 LTIP”) allows our Board of Directors to authorize share grants to be settled in cash or shares. Compensation expense for share awards to be settled in shares is measured at fair value on the date of grant and recognized on a straight-line basis over the requisite service period (usually the vesting period). Compensation expense for share awards to be settled in cash is remeasured each quarter with a cumulative adjustment to compensation cost during the period based on changes in our share price. Any adjustments to the compensation cost recognized in our consolidated statement of operations for awards that are forfeited are recognized in the period in which the forfeitures occur. See "Note 9 - Benefit Plans" for additional information on our share-based compensation. Fair Value Measurements We measure certain of our assets and liabilities based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy assigns the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities ("Level 1") and the lowest priority to unobservable inputs ("Level 3"). Level 2 measurements represent inputs that are observable for similar assets or liabilities, either directly or indirectly, other than quoted prices included within Level 1. See "Note 4 - Fair Value Measurements" for additional information on the fair value measurement of certain of our assets and liabilities. Noncontrolling Interests Third parties hold a noncontrolling ownership interest in certain of our non-U.S. subsidiaries. Noncontrolling interests are classified as equity on our consolidated balance sheet and net income attributable to noncontrolling interests is presented separately in our consolidated statement of operations. For each of the years in the three-year period ended December 31, 2018 , all income attributable to noncontrolling interest was from continuing operations. Earnings Per Share We compute basic and diluted earnings per share ("EPS") in accordance with the two-class method. Net income (loss) attributable to Ensco used in our computations of basic and diluted EPS is adjusted to exclude net income allocated to non-vested shares granted to our employees and non-employee directors. Weighted-average shares outstanding used in our computation of diluted EPS is calculated using the treasury stock method and includes the effect of all potentially dilutive performance awards and excludes non-vested shares. In each of the years in the three-year period ended December 31, 2018 , our potentially dilutive instruments were not included in the computation of diluted EPS as the effect of including these shares in the calculation would have been anti-dilutive. The following table is a reconciliation of income (loss) from continuing operations attributable to Ensco shares used in our basic and diluted EPS computations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Income (loss) from continuing operations attributable to Ensco $ (631.6 ) $ (304.7 ) $ 882.1 Income from continuing operations allocated to non-vested share awards (.5 ) (.4 ) (16.6 ) Income (loss) from continuing operations attributable to Ensco shares $ (632.1 ) $ (305.1 ) $ 865.5 Anti-dilutive share awards totaling 1.5 million , 2.0 million and 500,000 for the years ended December 31, 2018, 2017 and 2016 , respectively, were excluded from the computation of diluted EPS. During 2016, we issued our 3.00% exchangeable senior notes due 2024 (the "2024 Convertible Notes"). See "Note 6 - Debt" for additional information on this issuance. We have the option to settle the notes in cash, shares or a combination thereof for the aggregate amount due upon conversion. Our intent is to settle the principal amount of the 2024 Convertible Notes in cash upon conversion. If the conversion value exceeds the principal amount (i.e., our share price exceeds the exchange price on the date of conversion), we expect to deliver shares equal to the remainder of our conversion obligation in excess of the principal amount. During each respective reporting period that our average share price exceeds the exchange price, an assumed number of shares required to settle the conversion obligation in excess of the principal amount will be included in our denominator for the computation of diluted EPS using the treasury stock method. Our average share price did not exceed the exchange price during the years ended December 31, 2018 and December 31, 2017 . New Accounting Pronouncements Recently adopted accounting standards In August 2018, the Financial Accounting Standards Board (the "FASB") issued Update 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract ("Update 2018-15"), which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that included an internal-use software license). This update is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. We elected to early-adopt Update 2018-15 effective October 1, 2018. As a result of adopting Update 2018-15, we began deferring and amortizing certain costs incurred to implement cloud computing arrangements that would have been recognized as incurred under previous guidance. We do not expect our adoption of Update 2018-15 to have a material impact on our financial position or results of operations in future periods. In February 2018, 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 U.S. tax reform. 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 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 consolidated balance sheet as of January 1, 2017. 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. Recently issued accounting standards 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. However, we do not expect our adoption of Update 2017-12 to have a material impact on our financial position or results of operations. 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 July 2018, the FASB issued Accounting Standard Update 2018-11, Leases (Topic 842), Targeted Improvements, 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, by class of underlying asset, to not separate lease and non-lease components and account for the combined component under Topic 606 when the non-lease component is the predominant element of the combined component. The lessor practical expedient is limited to circumstances in which the lease, if accounted for separately, would be classified as an operating lease under Topic 842. While we are still finalizing our analysis, we believe the non-lease component of our contracts is the predominant element and that the lease component, if accounted for separately, would be classified as an operating lease. Accordingly, we expect that substantially all of our contracts will qualify for the practical expedient provided for in Update 2018-11. Therefore, we expect to elect the practical expedient prescribed in Update 2018-11 and account for the combined component as a single component under Topic 606. We do not expect our adoption to 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. With respect to leases whereby we are the lessee, we expect to recognize upon adoption on January 1, 2019 lease liabilities ranging from approximately $75 million to $80 million and offsetting "right of use" assets ranging from approximately $65 million to $70 million . Our adoption of Update 2016-02 is not expected to have a material impact on our ability to comply with current debt covenants. With the exception of the updated standards discussed above, there have been no accounting pronouncements issued and not yet effective that have significance, or potential significance, to our consolidated financial statements.

Revenues from Contracts with Cu

Revenues from Contracts with Customers	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	REVENUE FROM CONTRACTS WITH CUSTOMERS We provide drilling services on a day rate contract basis. Under day rate contracts, we provide an integrated service that includes the provision of a drilling rig and rig crews for which we receive a daily rate that may vary between the full rate and zero rate throughout the duration of the contractual term, depending on the operations of the rig. We also may receive lump-sum fees or similar compensation for the mobilization, demobilization and capital upgrades of our rigs. Our customers bear substantially all of the costs of constructing the well and supporting drilling operations, as well as the economic risk relative to the success of the well. Our integrated drilling service provided under each drilling contract is a single performance obligation satisfied over time and comprised of a series of distinct time increments, or service periods. Total revenue is determined for each individual drilling contract by estimating both fixed and variable consideration expected to be earned over the contract term. Fixed consideration generally relates to activities such as mobilization, demobilization and capital upgrades of our rigs that are not distinct within the context of our contracts and is recognized on a straight-line basis over the contract term. Variable consideration generally relates to distinct service periods during the contract term and is recognized in the period when the services are performed. The amount estimated for variable consideration is only recognized as revenue to the extent that it is probable that a significant reversal will not occur during the contract term. We have applied the optional exemption afforded in Update 2014-09 and have not disclosed the variable consideration related to our estimated future day rate revenues. The remaining duration of our drilling contracts based on those in place as of December 31, 2018 was between approximately one month and four years. Day Rate Drilling Revenue Our drilling contracts provide for payment on a day rate basis and include a rate schedule with higher rates for periods when the drilling unit is operating and lower rates or zero rates for periods when drilling operations are interrupted or restricted. The day rate invoiced to the customer is determined based on the varying rates applicable to specific activities performed on an hourly basis. Day rate consideration is allocated to the distinct hourly increment to which it relates within the contract term and is generally recognized consistent with the contractual rate invoiced for the services provided during the respective period. Invoices are typically issued to our customers on a monthly basis and payment terms on customer invoices typically range from 30 to 45 days. Certain of our contracts contain performance incentives whereby we may earn a bonus based on pre-established performance criteria. Such incentives are generally based on our performance over individual monthly time periods or individual wells. Consideration related to performance bonus is generally recognized in the specific time period to which the performance criteria was attributed. We may receive termination fees if certain drilling contracts are terminated by the customer prior to the end of the contractual term. Such compensation is recognized as revenue when our performance obligation is satisfied, the termination fee can be reasonably measured and collection is probable. For the year ended December 31, 2017 , operating revenues included $185.0 million for the lump-sum consideration received in settlement and release of the ENSCO DS-9 customer's ongoing early termination obligations. For the year ended December 31, 2016, operating revenues included $20.0 million for the lump-sum consideration received in settlement of the ENSCO 8503 customer's remaining obligations under the contract. Mobilization / Demobilization Revenue In connection with certain contracts, we receive lump-sum fees or similar compensation for the mobilization of equipment and personnel prior to the commencement of drilling services or the demobilization of equipment and personnel upon contract completion. Fees received for the mobilization or demobilization of equipment and personnel are included in operating revenues. The costs incurred in connection with the mobilization and demobilization of equipment and personnel are included in contract drilling expense. Mobilization fees received prior to commencement of drilling operations are recorded as a contract liability and amortized on a straight-line basis over the contract term. Demobilization fees expected to be received upon contract completion are estimated at contract inception and recognized on a straight-line basis over the contract term. In some cases, demobilization fees may be contingent upon the occurrence or non-occurrence of a future event. In such cases, this may result in cumulative-effect adjustments to demobilization revenues upon changes in our estimates of future events during the contract term. Capital Upgrade / Contract Preparation Revenue In connection with certain contracts, we receive lump-sum fees or similar compensation for requested capital upgrades to our drilling rigs or for other contract preparation work. Fees received for requested capital upgrades and other contract preparation work are recorded as a contract liability and amortized on a straight-line basis over the contract term to operating revenues. Costs incurred for capital upgrades are capitalized and depreciated over the useful life of the asset. Contract Assets and Liabilities Contract assets represent amounts recognized as revenue but for which the right to invoice the customer is dependent upon our future performance. Once the previously recognized revenue is invoiced, the corresponding contract asset, or a portion thereof, is transferred to accounts receivable. Contract liabilities generally represent fees received for mobilization or capital upgrades. Contract assets and liabilities are presented net on our consolidated balance sheet on a contract-by-contract basis. Current contract assets and liabilities are included in other current assets and accrued liabilities and other, respectively, and noncurrent contract assets and liabilities are included in other assets and other liabilities, respectively, on our consolidated balance sheets. The following table summarizes our contract assets and contract liabilities (in millions): December 31, 2018 December 31, 2017 Current contract assets $ 4.0 $ 3.0 Noncurrent contract assets $ — $ 2.8 Current contract liabilities (deferred revenue) $ 56.9 $ 71.9 Noncurrent contract liabilities (deferred revenue) $ 20.5 $ 51.2 Changes in contract assets and liabilities during the period are as follows (in millions): Contract Assets Contract Liabilities Balance as of December 31, 2017 $ 5.8 $ 123.1 Revenue recognized in advance of right to bill customer 2.2 — Increase due to cash received — 49.4 Decrease due to amortization of deferred revenue that was included in the beginning contract liability balance — (72.0 ) Decrease due to amortization of deferred revenue that was added during the period — (23.1 ) Decrease due to transfer to receivables during the period (4.0 ) — Balance as of December 31, 2018 $ 4.0 $ 77.4 Deferred Contract Costs Costs incurred for upfront rig mobilizations and certain contract preparations are attributable to our future performance obligation under each respective drilling contract. Such costs are deferred and amortized on a straight-line basis over the contract term. Demobilization costs are recognized as incurred upon contract completion. Costs associated with the mobilization of equipment and personnel to more promising market areas without contracts are expensed as incurred. Deferred contract costs were included in other current assets and other assets on our consolidated balance sheets and totaled $23.5 million and $40.6 million as of December 31, 2018 and 2017 , respectively. Amortization of such costs totaled $34.0 million , $28.1 million and $42.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Deferred Certification Costs We must obtain certifications from various regulatory bodies in order to operate our drilling rigs and must maintain such certifications through periodic inspections and surveys. The costs incurred in connection with maintaining such certifications, including inspections, tests, surveys and drydock, as well as remedial structural work and other compliance costs, are deferred and amortized on a straight-line basis over the corresponding certification periods. Deferred regulatory certification and compliance costs were included in other current assets and other assets on our consolidated balance sheets and totaled $13.6 million and $15.3 million as of December 31, 2018 and 2017 , respectively. Amortization of such costs totaled $12.4 million , $12.1 million and $16.8 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Future Amortization of Contract Liabilities and Deferred Costs Our contract liabilities and deferred costs are amortized on a straight-line basis over the contract term or corresponding certification period to operating revenues and contract drilling expense, respectively. Expected future amortization of our contract liabilities and deferred costs recorded as of December 31, 2018 is set forth in the table below (in millions): 2019 2020 2021 2022 and Thereafter Total Amortization of contract liabilities $ 57.0 $ 11.7 $ 7.2 $ 1.5 $ 77.4 Amortization of deferred costs $ 23.8 $ 9.4 $ 2.4 $ 1.5 $ 37.1

Acquisition Of Atwood

Acquisition Of Atwood	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combination Disclosure	ACQUISITION OF ATWOOD On the Merger Date, we completed the Atwood Merger with Atwood and Echo Merger Sub, LLC, our wholly-owned subsidiary. Assets acquired and liabilities assumed in the Atwood Merger were recorded at their estimated fair values as of the Merger Date under the acquisition method of accounting. As of September 30, 2018, we completed our fair value assessments. Consideration As a result of the Atwood Merger, Atwood shareholders received 1.60 Ensco Class A Ordinary shares for each share of Atwood common stock, representing a value of $9.33 per share of Atwood common stock based on a closing price of $5.83 per Class A ordinary share on October 5, 2017, the last trading day before the Merger Date. Total consideration delivered in the Atwood Merger consisted of 132.2 million of our Class A ordinary shares and $11.1 million of cash in settlement of certain share-based payment awards. The total aggregate value of consideration transferred was $781.8 million . Additionally, upon closing of the Atwood Merger, we utilized cash acquired of $445.4 million and cash on hand to extinguish Atwood's revolving credit facility, outstanding senior notes and accrued interest totaling $1.3 billion . The estimated fair values assigned to assets acquired net of liabilities assumed exceeded the consideration transferred, resulting in a bargain purchase gain of $140.2 million that was recognized during the fourth quarter of 2017. During 2018, we recognized measurement period adjustments as we completed our fair value assessments resulting in additional bargain purchase gain of $1.8 million . Bargain purchase gain was included in other, net, in our consolidated statements of operations. Assets Acquired and Liabilities Assumed The provisional amounts recorded for assets acquired and liabilities assumed as of the Merger Date and respective measurement period adjustments were as follows (in millions): Amounts Recognized as of Merger Date Measurement Period Adjustments (1) Estimated Fair Value Assets: Cash and cash equivalents (2) $ 445.4 $ — $ 445.4 Accounts receivable (3) 62.3 (1.6 ) 60.7 Other current assets 118.1 4.6 122.7 Property and equipment 1,762.0 9.2 1,771.2 Other assets 23.7 (5.1 ) 18.6 Liabilities: Accounts payable and accrued liabilities 64.9 (1.1 ) 63.8 Other liabilities 118.7 6.4 125.1 Net assets acquired 2,227.9 1.8 2,229.7 Less: Merger consideration (781.8 ) (781.8 ) Repayment of Atwood debt (2) (1,305.9 ) (1,305.9 ) Bargain purchase gain $ 140.2 $ 142.0 (1) The measurement period adjustments reflect changes in the estimated fair values of certain assets and liabilities, primarily related to inventory, capital equipment and other liabilities. The measurement period adjustments were recorded to reflect new information obtained about facts and circumstances existing as of the Merger Date and did not result from subsequent intervening events. (2) Upon closing of the Atwood Merger, we utilized acquired cash of $445.4 million and cash on hand from the liquidation of short-term investments to repay Atwood's debt and accrued interest of $1.3 billion . (3) Gross contractual amounts receivable totaled $64.7 million as of the Merger Date. Bargain Purchase Gain The fair values assigned to assets acquired net of liabilities assumed exceeded the consideration transferred, resulting in a bargain purchase gain primarily due to depressed offshore drilling company valuations. Market capitalizations across the offshore drilling industry declined significantly since mid-2014 due to the decline in commodity prices and the related imbalance of supply and demand for drilling rigs. The resulting bargain purchase gain was further driven by the decline in our share price from $6.70 to $5.83 between the last trading day prior to the announcement of the Atwood Merger and the Merger Date. Merger-Related Costs Merger-related costs were expensed as incurred and consisted of various advisory, legal, accounting, valuation and other professional or consulting fees totaling $19.4 million for the year ended December 31, 2017. These costs are included in general and administrative expense in our consolidated statements of operations. Property and Equipment Property and equipment acquired in connection with the Atwood Merger consisted primarily of drilling rigs and related equipment, including four drillships ( two of which are under construction), two semisubmersible rigs and five jackup rigs. We recorded property and equipment acquired at its estimated fair value of $1.8 billion . We estimated the fair value of the rigs and equipment by applying an income approach, using projected discounted cash flows, or a market approach. We estimated remaining useful lives for Atwood's drilling rigs, which ranged from 16 to 35 years based on original estimated useful lives of 30 to 35 years. Deferred Taxes The Atwood Merger was executed through the acquisition of Atwood's outstanding common stock and, therefore, the historical tax bases of the acquired assets and assumed liabilities, net operating losses and other tax attributes of Atwood were assumed as of the Merger Date. However, adjustments were recorded to recognize deferred tax assets and liabilities for the tax effects of differences between acquisition date fair values and tax bases of assets acquired and liabilities assumed. Additionally, the interaction of our and Atwood's tax attributes that impacted the deferred taxes of the combined entity were also recognized as part of acquisition accounting. As of the Merger Date, an increase of $2.5 million to Atwood’s net deferred tax liability was recognized. Deferred tax assets and liabilities recognized in connection with the Atwood Merger were measured at rates enacted as of the Merger Date. Tax rate changes, or any deferred tax adjustments for new tax legislation, following the Merger Date, including the recently enacted U.S. tax reform, are reflected in our operating results in the period in which the change in tax laws or rate is enacted. Intangible Assets and Liabilities We recorded intangible assets totaling $30.1 million , inclusive of certain measurement period adjustments, as of the Merger Date representing the estimated fair value of Atwood's firm drilling contracts with favorable contract terms compared to then-market day rates for comparable drilling rigs. Operating revenues were net of $11.4 million and $16.1 million of asset amortization during the years ended December 31, 2018 and 2017 , respectively. The remaining balance of $2.6 million was included in other assets on our consolidated balance sheet as of December 31, 2018 and will be amortized to operating revenue during 2019 . We recorded intangible liabilities of $60.0 million for the estimated fair value of unfavorable drillship construction contracts, which were determined by comparing the firm obligations for the remaining construction of ENSCO DS-13 and ENSCO DS-14 to the estimated current market rates for the construction of a comparable drilling rig. The liabilities will be amortized over the estimated life of ENSCO DS-13 and ENSCO DS-14 as a reduction of depreciation expense beginning on the date the rig is placed into service. Pro Forma Impact of the Atwood Merger The following unaudited supplemental pro forma results present consolidated information as if the Atwood Merger was completed on January 1, 2016. The pro forma results include, among others, (i) the amortization associated with acquired intangible assets and liabilities, (ii) a reduction in depreciation expense for adjustments to property and equipment and (iii) a reduction to interest expense resulting from the retirement of Atwood's revolving credit facility and 6.50% senior notes due 2020. The pro forma results do not include any potential synergies or non-recurring charges resulting directly from the Atwood Merger. (in millions, except per share amounts) Twelve Months Ended (Unaudited) 2017 (1) 2016 Revenues $ 2,226.0 $ 3,622.1 Net income (loss) (347.0 ) 1,284.9 Earnings (loss) per share - basic and diluted (.80 ) 3.18 (1) Pro forma net income and earnings per share were adjusted to exclude an aggregate $80.7 million of merger-related and integration costs incurred by Ensco and Atwood during 2017 and the $140.2 million estimated bargain purchase gain.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following fair value hierarchy table categorizes information regarding our net financial assets measured at fair value on a recurring basis as of December 31, 2018 and 2017 (in millions): Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total As of December 31, 2018 Supplemental executive retirement plan assets $ 27.2 $ — $ — $ 27.2 Total financial assets 27.2 — — 27.2 Derivatives, net — (10.7 ) — (10.7 ) Total financial liabilities $ — $ (10.7 ) $ — $ (10.7 ) As of December 31, 2017 Supplemental executive retirement plan assets $ 30.9 $ — $ — $ 30.9 Derivatives, net — 6.8 — 6.8 Total financial assets $ 30.9 $ 6.8 $ — $ 37.7 Supplemental Executive Retirement Plans Our Ensco supplemental executive retirement plans (the "SERPs") are non-qualified plans that provide for eligible employees to defer a portion of their compensation for use after retirement. Assets held in the SERP were marketable securities measured at fair value on a recurring basis using Level 1 inputs and were included in other assets, net, on our consolidated balance sheets as of December 31, 2018 and 2017 . The fair value measurements of assets held in the SERP were based on quoted market prices. Net unrealized losses of $700,000 and gains of $4.5 million and $1.8 million from marketable securities held in our SERP were included in other, net, in our consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 , respectively. Derivatives Our derivatives were measured at fair value on a recurring basis using Level 2 inputs as of December 31, 2018 and 2017 . See "Note 7 - Derivative Instruments" for additional information on our derivatives, including a description of our foreign currency hedging activities and related methodologies used to manage foreign currency exchange rate risk. The fair value measurements of our derivatives were based on market prices that are generally observable for similar assets or liabilities at commonly quoted intervals. Other Financial Instruments The carrying values and estimated fair values of our debt instruments as of December 31, 2018 and 2017 were as follows (in millions): December 31, 2018 December 31, 2017 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value 8.50% Senior notes due 2019 (1) $ — $ — $ 251.4 $ 252.9 6.875% Senior notes due 2020 (1) 127.5 121.6 477.9 473.1 4.70% Senior notes due 2021 (1) 112.7 101.8 267.1 265.3 3.00% Exchangeable senior notes due 2024 (2) 666.8 575.5 635.7 757.1 4.50% Senior notes due 2024 619.8 405.2 619.3 527.1 8.00% Senior notes due 2024 337.0 273.7 337.9 333.8 5.20% Senior notes due 2025 664.4 443.9 663.6 571.4 7.75% Senior notes due 2026 985.0 725.5 — — 7.20% Debentures due 2027 149.3 109.1 149.3 141.9 7.875% Senior notes due 2040 375.0 223.2 376.7 258.8 5.75% Senior notes due 2044 972.9 566.3 971.8 690.4 Total $ 5,010.4 $ 3,545.8 $ 4,750.7 $ 4,271.8 (1) The decline in the carrying value of our 8.50% senior notes due 2019, 6.875% senior notes due 2020 and our 4.70% senior notes due 2021 from December 31, 2017 to December 31, 2018 is primarily due to debt repurchases and redemptions as discussed in "Note 6 - Debt". (2) Our 3.00% exchangeable senior notes due 2024 (the "2024 Convertible Notes") were issued with a conversion feature. The 2024 Convertible Notes were separated into their liability and equity components on our consolidated balance sheet. The equity component was initially recorded to additional paid-in capital and as a debt discount, which will be amortized to interest expense. Excluding the unamortized discount, the carrying value of the 2024 Convertible Notes was $836.3 million and $834.0 million as of December 31, 2018 and 2017 . See "Note 6 - Debt" for additional information on this issuance. The estimated fair values of our senior notes and debentures were determined using quoted market prices. The estimated fair values of our cash and cash equivalents, short-term investments, receivables, trade payables and other liabilities approximated their carrying values as of December 31, 2018 and 2017 .

Property And Equipment

Property And Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property And Equipment	PROPERTY AND EQUIPMENT Property and equipment as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Drilling rigs and equipment $ 14,542.5 $ 12,272.4 Work-in-progress 779.2 2,876.3 Other 195.3 183.4 $ 15,517.0 $ 15,332.1 Work-in-progress as of December 31, 2018 primarily consisted of $416.8 million related to the construction of ultra-deepwater drillships ENSCO DS-13 and ENSCO DS-14 and $352.4 million related to the construction of ENSCO 123, an ultra-premium harsh environment jackup rig. Work-in-progress as of December 31, 2017 primarily consisted of $2.0 billion related to the construction of ultra-deepwater drillships ENSCO DS-9, ENSCO DS-10, ENSCO DS-13 and ENSCO DS-14, $423.6 million related to the construction of premium jackup rigs ENSCO 140 and ENSCO 141 and $321.6 million related to the construction of ENSCO 123, an ultra-premium harsh environment jackup rig. ENSCO DS-9, ENSCO DS-10, ENSCO 140 and ENSCO 141 were placed into service and reclassified from work-in-progress to drilling rigs and equipment during the year ended December 31, 2018 . Impairment of Long-Lived Assets On a quarterly basis, we evaluate the carrying value of our property and equipment to identify events or changes in circumstances ("triggering events") that indicate the carrying value may not be recoverable. During 2018, we recorded a pre-tax, non-cash loss on impairment of $40.3 million related to one older non-core jackup rig. During the fourth quarter, we concluded that a triggering event occurred due to the expiration of a legacy higher day rate contract resulting in the performance of a recoverability test. We determined that the estimated undiscounted cash flows over the remaining useful life of the rig were not sufficient to recover the rig’s carrying value and concluded the rig was impaired as of December 31, 2018. During 2017, we recognized a pre-tax, non-cash loss on impairment of $182.9 million related to older, less capable, non-core assets in our fleet. During the fourth quarter, we determined that the remaining useful life of certain non-core rigs would not extend substantially beyond their current contracts, resulting in triggering events and the performance of recoverability tests. Our estimates of undiscounted cash flows over the revised estimated remaining useful lives were not sufficient to recover each asset’s carrying value. Accordingly, we concluded that two semisubmersibles and one jackup were impaired as of December 31, 2017. For rigs whose carrying values were determined not to be recoverable during 2018 and 2017, we recorded an impairment for the difference between their fair values and carrying values. We estimated the fair values of these rigs by applying an income approach, using projected discounted cash flows. These valuations were based on unobservable inputs that require significant judgments for which there is limited information, including assumptions regarding future day rates, utilization, operating costs and capital requirements. Forecasted day rates and utilization took into account market conditions and our anticipated business outlook. If the global economy, our overall business outlook and/or our expectations regarding the marketability of one or more of our drilling rigs deteriorate further, we may conclude that a triggering event has occurred and perform a recoverability test that could lead to a material impairment charge in future periods.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	DEBT The carrying value of our long-term debt as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 8.50% Senior notes due 2019 (1) $ — $ 251.4 6.875% Senior notes due 2020 (1) 127.5 477.9 4.70% Senior notes due 2021 (1) 112.7 267.1 3.00% Exchangeable senior notes due 2024 (2) 666.8 635.7 4.50% Senior notes due 2024 619.8 619.3 8.00% Senior notes due 2024 337.0 337.9 5.20% Senior notes due 2025 664.4 663.6 7.75% Senior notes due 2026 985.0 — 7.20% Debentures due 2027 149.3 149.3 7.875% Senior notes due 2040 375.0 376.7 5.75% Senior notes due 2044 972.9 971.8 Total long-term debt $ 5,010.4 $ 4,750.7 (1) The decline in the carrying value of our 8.50% senior notes due 2019, 6.875% senior notes due 2020 and our 4.70% senior notes due 2021 resulted from repurchases and redemptions during the first quarter of 2018 discussed below. (2) Our 2024 Convertible Notes were issued with a conversion feature. The 2024 Convertible Notes were separated into their liability and equity components on our consolidated balance sheet. The equity component was initially recorded to additional paid-in capital and as a debt discount that will be amortized to interest expense over the life of the instrument. Excluding the unamortized discount, the carrying value of the 2024 Convertible Notes was $836.3 million and $834.0 million as of December 31, 2018 and 2017 , respectively. 2024 Convertible Notes In December 2016, Ensco Jersey Finance Limited, a wholly-owned subsidiary of Ensco plc, issued $849.5 million aggregate principal amount of unsecured 2024 Convertible Notes in a private offering. The 2024 Convertible Notes are fully and unconditionally guaranteed, on a senior, unsecured basis, by Ensco plc and are exchangeable into cash, our Class A ordinary shares or a combination thereof, at our election. Interest on the 2024 Convertible Notes is payable semiannually on January 31 and July 31 of each year. The 2024 Convertible Notes will mature on January 31, 2024, unless exchanged, redeemed or repurchased in accordance with their terms prior to such date. Holders may exchange their 2024 Convertible Notes at their option any time prior to July 31, 2023 only under certain circumstances set forth in the indenture governing the 2024 Convertible Notes. On or after July 31, 2023, holders may exchange their 2024 Convertible Notes at any time. The exchange rate is 71.3343 shares per $1,000 principal amount of notes, representing an exchange price of $14.02 per share, and is subject to adjustment upon certain events. The 2024 Convertible Notes may not be redeemed by us except in the event of certain tax law changes. Upon conversion of the 2024 Convertible Notes, holders will receive cash, our Class A ordinary shares or a combination thereof, at our election. Our intent is to settle the principal amount of the 2024 Convertible Notes in cash upon conversion. If the conversion value exceeds the principal amount (i.e., our share price exceeds the exchange price on the date of conversion), we expect to deliver shares equal to our conversion obligation in excess of the principal amount. During each respective reporting period that our average share price exceeds the exchange price, an assumed number of shares required to settle the conversion obligation in excess of the principal amount will be included in the denominator for our computation of diluted EPS using the treasury stock method. See "Note 1 - Description of the Business and Summary of Significant Accounting Policies" for additional information regarding the impact to our EPS. The 2024 Convertible Notes were separated into their liability and equity components and included in long-term debt and additional paid-in capital on our consolidated balance sheet, respectively. The carrying amount of the liability component was calculated by measuring the estimated fair value of a similar liability that does not include an associated conversion feature. The carrying amount of the equity component representing the conversion feature was determined by deducting the fair value of the liability component from the principal amount of the 2024 Convertible Notes. The difference between the carrying amount of the liability and the principal amount is amortized to interest expense over the term of the 2024 Convertible Notes, together with the coupon interest, resulting in an effective interest rate of approximately 8% per annum. The equity component is not remeasured if we continue to meet certain conditions for equity classification. The costs related to the issuance of the 2024 Convertible Notes were allocated to the liability and equity components based on their relative fair values. Issuance costs attributable to the liability component are amortized to interest expense over the term of the notes and the issuance costs attributable to the equity component were recorded to additional paid-in capital on our consolidated balance sheet. As of December 31, 2018 and 2017 , the 2024 Convertible Notes consist of the following (in millions): Liability component: 2018 2017 Principal $ 849.5 $ 849.5 Less: Unamortized debt discount and issuance costs (182.7 ) (213.8 ) Net carrying amount 666.8 635.7 Equity component, net $ 220.0 $ 220.0 During the year ended December 31, 2018 , we recognized $25.5 million associated with coupon interest and $31.0 million associated with the amortization of debt discount and issuance costs. During the year ended December 31, 2017 , we recognized $25.5 million associated with coupon interest and $31.4 million associated the amortization of debt discount and issuance costs. The indenture governing the 2024 Convertible Notes contains customary events of default, including failure to pay principal or interest on such notes when due, among others. The indenture also contains certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create or incur secured indebtedness, enter into certain sale/leaseback transactions and enter into certain merger or consolidation transactions. Senior Notes On January 26, 2018, we issued $1.0 billion aggregate principal amount of unsecured 7.75% senior notes due 2026 (the "2026 Notes") at par, net of $16.5 million of debt issuance costs. Interest on the 2026 Notes is payable semiannually on February 1 and August 1 of each year. During 2017, we exchanged $332.0 million aggregate principal amount of unsecured 8.00% senior notes due 2024 (the “8 % 2024 Notes”) for certain amounts of our outstanding senior notes due 2019, 2020 and 2021. Interest on the 8% 2024 Notes is payable semiannually on January 31 and July 31 of each year. During 2015, we issued $700.0 million aggregate principal amount of unsecured 5.20% senior notes due 2025 (the “2025 Notes”) at a discount of $2.6 million and $400.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the “New 2044 Notes”) at a discount of $18.7 million in a public offering. Interest on the 2025 Notes is payable semiannually on March 15 and September 15 of each year. Interest on the New 2044 Notes is payable semiannually on April 1 and October 1 of each year. During 2014, we issued $625.0 million aggregate principal amount of unsecured 4.50% senior notes due 2024 (the "2024 Notes") at a discount of $850,000 and $625.0 million aggregate principal amount of unsecured 5.75% senior notes due 2044 (the "Existing 2044 Notes" and together with the New 2044 Notes, the "2044 Notes") at a discount of $2.8 million . Interest on the 2024 Notes and the Existing 2044 Notes is payable semiannually on April 1 and October 1 of each year. The Existing 2044 Notes and the New 2044 Notes are treated as a single series of debt securities under the indenture governing the notes. During 2011, we issued $1.5 billion aggregate principal amount of unsecured 4.70% senior notes due 2021 (the “2021 Notes”) at a discount of $29.6 million in a public offering. Interest on the 2021 Notes is payable semiannually on March 15 and September 15 of each year. Upon consummation of the Pride acquisition during 2011, we assumed outstanding debt comprised of $900.0 million aggregate principal amount of unsecured 6.875% senior notes due 2020 , $500.0 million aggregate principal amount of unsecured 8.5% senior notes due 2019 and $300.0 million aggregate principal amount of unsecured 7.875% senior notes due 2040 (collectively, the "Acquired Notes" and together with the 2021 Notes, 8% 2024 Notes, 2024 Notes, 2025 Notes, 2026 Notes and 2044 Notes, the "Senior Notes"). Ensco plc has fully and unconditionally guaranteed the performance of all Pride obligations with respect to the Acquired Notes. See " Note 15 - Guarantee of Registered Securities " for additional information on the guarantee of the Acquired Notes. We may redeem the 8% 2024 Notes, 2024 Notes, 2025 Notes, 2026 Notes and 2044 Notes in whole at any time, or in part from time to time, prior to maturity. If we elect to redeem the 8% 2024 Notes, 2024 Notes, 2025 Notes and 2026 Notes before the date that is three months prior to the maturity date or the 2044 Notes before the date that is six months prior to the maturity date, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest and a "make-whole" premium. If we elect to redeem the 8% 2024 Notes, 2024 Notes, 2025 Notes, 2026 Notes or 2044 Notes on or after the aforementioned dates, we will pay an amount equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest but we are not required to pay a "make-whole" premium. We may redeem each series of the 2021 Notes and the Acquired Notes, in whole or in part, at any time at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a "make-whole" premium. The indentures governing the Senior Notes contain customary events of default, including failure to pay principal or interest on such notes when due, among others. The indentures governing the Senior Notes also contain certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create or incur secured indebtedness, enter into certain sale/leaseback transactions and enter into certain merger or consolidation transactions. Debentures Due 2027 During 1997, Ensco International Incorporated issued $150.0 million of unsecured 7.20% Debentures due 2027 (the "Debentures"). Interest on the Debentures is payable semiannually on May 15 and November 15 of each year. We may redeem the Debentures, in whole or in part, at any time prior to maturity, at a price equal to 100% of their principal amount, plus accrued and unpaid interest and a "make-whole" premium. During 2009, Ensco plc entered into a supplemental indenture to unconditionally guarantee the principal and interest payments on the Debentures. See " Note 15 - Guarantee of Registered Securities " for additional information on the guarantee of the Debentures. The Debentures and the indenture pursuant to which the Debentures were issued also contain customary events of default, including failure to pay principal or interest on the Debentures when due, among others. The indenture also contains certain restrictions, including, among others, restrictions on our ability and the ability of our subsidiaries to create or incur secured indebtedness, enter into certain sale/leaseback transactions and enter into certain merger or consolidation transactions. Tender Offers, Redemptions and Open Market Repurchases Concurrent with the issuance of the 2026 Notes in January 2018, we launched cash tender offers for up to $985.0 million aggregate principal amount of certain series of our senior notes issued by us and Pride. The tender offers expired February 7, 2018, and we repurchased $182.6 million of our 8.50% senior notes due 2019, $256.6 million of our 6.875% senior notes due 2020 and $156.2 million of the 2021 Notes. Subsequently, we issued a redemption notice for the remaining outstanding $55.0 million principal amount of the 8.50% senior notes due 2019 and repurchased $71.4 million principal amount of our senior notes due 2020. As a result of these transactions, we recognized a pre-tax loss from debt extinguishment of $19.0 million , net of discounts, premiums, debt issuance costs and commissions during the first quarter of 2018. During 2017, we repurchased $194.1 million of our outstanding senior notes on the open market for an aggregate purchase price of $204.5 million with cash on hand and recognized an insignificant pre-tax gain, net of discounts, premiums and debt issuance costs. Our tender offers and open market repurchases during the two-year period ended December 31, 2018 were as follows (in millions): Year Ended December 31, 2018 Aggregate Principal Amount Repurchased Aggregate Repurchase Price (1) 8.50% Senior notes due 2019 $ 237.6 $ 256.8 6.875% Senior notes due 2020 328.0 354.7 4.70% Senior notes due 2021 156.2 159.7 Total $ 721.8 $ 771.2 Year Ended December 31, 2017 Aggregate Principal Amount Repurchased Aggregate Repurchase Price (1) 8.50% Senior notes due 2019 $ 54.6 $ 60.1 6.875% Senior notes due 2020 100.1 105.1 4.70% Senior notes due 2021 39.4 39.3 Total $ 194.1 $ 204.5 (1) Excludes accrued interest paid to holders of the repurchased senior notes. Exchange Offers During 2017, we completed exchange offers to exchange our outstanding 2019 Notes, 2020 Notes and 2021 Notes for our 8% 2024 Notes and cash. The exchange offers resulted in the tender of $649.5 million aggregate principal amount of our outstanding notes that were settled and exchanged as follows (in millions): Aggregate Principal Amount Repurchased 8% Senior Notes Due 2024 Consideration Cash Total Consideration 8.50% Senior notes due 2019 $ 145.8 $ 81.6 $ 81.7 $ 163.3 6.875% Senior notes due 2020 129.8 69.3 69.4 138.7 4.70% Senior notes due 2021 373.9 181.1 181.4 362.5 Total $ 649.5 $ 332.0 $ 332.5 $ 664.5 During the year ended December 31, 2017, we recognized a pre-tax loss on the exchange offers of approximately $6.2 million , consisting of a loss of $3.5 million that includes the write-off of premiums on tendered debt and $2.7 million of transaction costs. Debt to Equity Exchange During 2016, we entered into a privately-negotiated exchange agreement whereby we issued 1,822,432 Class A ordinary shares, representing less than one percent of our outstanding shares, in exchange for $24.5 million principal amount of our 2044 Notes, resulting in a pre-tax gain from debt extinguishment of $8.8 million . Revolving Credit In October 2017, we amended our revolving credit facility ("Credit Facility") to extend the final maturity date by two years. Previously, our Credit Facility had a borrowing capacity of $2.25 billion through September 2019 that declined to $1.13 billion through September 2020. Subsequent to the amendment, our borrowing capacity is $2.0 billion through September 2019 and declines to $1.3 billion through September 2020 and to $1.2 billion through September 2022. The credit agreement governing our Credit Facility includes an accordion feature allowing us to increase the commitments expiring in September 2022 up to an aggregate amount not to exceed $1.5 billion . Advances under the Credit Facility bear interest at Base Rate or LIBOR plus an applicable margin rate, depending on our credit ratings. We are required to pay a quarterly commitment fee on the undrawn portion of the $2.0 billion commitment, which is also based on our credit ratings. In January 2018, Moody's downgraded our senior unsecured bond credit rating from B2 to B3. The rating actions resulted in an increase to the interest rates applicable to our borrowings and the quarterly commitment fee on the undrawn portion of the $2.0 billion commitment. The applicable margin rates are 3.00% per annum for Base Rate advances and 4.00% per annum for LIBOR advances. The quarterly commitment fee is 0.75% per annum on the undrawn portion of the $2.0 billion commitment. The Credit Facility requires us to maintain a total debt to total capitalization ratio that is less than or equal to 60% and to provide guarantees from certain of our rig-owning subsidiaries sufficient to meet certain guarantee coverage ratios. The Credit Facility also contains customary restrictive covenants, including, among others, prohibitions on creating, incurring or assuming certain debt and liens (subject to customary exceptions, including a permitted lien basket that permits us to raise secured debt up to the lesser of $750 million or 10% of consolidated tangible net worth (as defined in the Credit Facility)); entering into certain merger arrangements; selling, leasing, transferring or otherwise disposing of all or substantially all of our assets; making a material change in the nature of the business; paying or distributing dividends on our ordinary shares (subject to certain exceptions, including the ability to continue paying a quarterly dividend of $0.01 per share); borrowings, if after giving effect to any such borrowings and the application of the proceeds thereof, the aggregate amount of available cash (as defined in the Credit Facility) would exceed $150 million ; and entering into certain transactions with affiliates. The Credit Facility also includes a covenant restricting our ability to repay indebtedness maturing after September 2022, which is the final maturity date of our Credit Facility. This covenant is subject to certain exceptions that permit us to manage our balance sheet, including the ability to make repayments of indebtedness (i) of acquired companies within 90 days of the completion of the acquisition or (ii) if, after giving effect to such repayments, available cash is greater than $250 million and there are no amounts outstanding under the Credit Facility. As of December 31, 2018 , we were in compliance in all material respects with our covenants under the Credit Facility. We expect to remain in compliance with our Credit Facility covenants during 2019 . We had no amounts outstanding under the Credit Facility as of December 31, 2018 and 2017 . Our access to credit and capital markets depends on the credit ratings assigned to our debt. As a result of recent rating actions by credit rating agencies, we no longer maintain an investment-grade status. Our current credit ratings, and any additional actual or anticipated downgrades in our credit ratings, could limit our available options when accessing credit and capital markets, or when restructuring or refinancing our debt. In addition, future financings or refinancings may result in higher borrowing costs and require more restrictive terms and covenants, which may further restrict our operations. Maturities The descriptions of our senior notes above reflect the original principal amounts issued, which have subsequently changed as a result of our tenders, repurchases, exchanges, redemptions and new debt issuances such that the maturities of our debt were as follows (in millions): Senior Notes Original Principal 2016 Tenders, Repurchases and Equity Exchange 2017 Exchange Offers and Repurchases 2018 Tender Offers, Redemption and Debt Issuance Remaining Principal 8.50% due 2019 $ 500.0 $ (62.0 ) $ (200.4 ) $ (237.6 ) $ — 6.875% due 2020 900.0 (219.2 ) (229.9 ) (328.0 ) 122.9 4.70% due 2021 1,500.0 (817.0 ) (413.3 ) (156.2 ) 113.5 3.00% Exchangeable senior notes due 2024 849.5 — — — 849.5 4.50% due 2024 625.0 (1.7 ) — — 623.3 8.00% due 2024 — — 332.0 — 332.0 5.20% due 2025 700.0 (30.7 ) — — 669.3 7.75% due 2026 — — — 1,000.0 1,000.0 7.20% due 2027 150.0 — — — 150.0 7.875% due 2040 300.0 — — — 300.0 5.75% due 2044 1,025.0 (24.5 ) — — 1,000.5 Total $ 6,549.5 $ (1,155.1 ) $ (511.6 ) $ 278.2 $ 5,161.0 Interest Expense Interest expense totaled $282.7 million , $224.2 million and $228.8 million for the years ended December 31, 2018, 2017 and 2016 , respectively, which was net of capitalized interest of $62.6 million , $72.5 million and $45.7 million associated with newbuild rig construction and other capital projects.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS We use derivatives to reduce our exposure to various market risks, primarily foreign currency exchange rate risk. We maintain a foreign currency exchange rate risk management strategy that utilizes derivatives to reduce our exposure to unanticipated fluctuations in earnings and cash flows caused by changes in foreign currency exchange rates. We mitigate our credit risk relating to the counterparties of our derivatives by transacting with multiple, high-quality financial institutions, thereby limiting exposure to individual counterparties, and by entering into International Swaps and Derivatives Association, Inc. (“ISDA”) Master Agreements, which include provisions for a legally enforceable master netting agreement, with our derivative counterparties. See "Note 14 - Supplemental Financial Information" for additional information on the mitigation of credit risk relating to counterparties of our derivatives. We do not enter into derivatives for trading or other speculative purposes. All derivatives were recorded on our consolidated balance sheets at fair value. Derivatives subject to legally enforceable master netting agreements were not offset on our consolidated balance sheets. Accounting for the gains and losses resulting from changes in the fair value of derivatives depends on the use of the derivative and whether it qualifies for hedge accounting. See "Note 1 - Description of the Business and Summary of Significant Accounting Policies" for additional information on our accounting policy for derivatives and "Note 4 - Fair Value Measurements" for additional information on the fair value measurement of our derivatives. As of December 31, 2018 and 2017 , our consolidated balance sheets included net foreign currency derivative liabilities of $10.7 million and assets of $6.8 million , respectively. All of our derivatives mature within the next 18 months. Derivatives recorded at fair value on our consolidated balance sheets as of December 31, 2018 and 2017 consisted of the following (in millions): Derivative Assets Derivative Liabilities 2018 2017 2018 2017 Derivatives Designated as Hedging Instruments Foreign currency forward contracts - current (1) $ .2 $ 5.9 $ 8.3 $ .2 Foreign currency forward contracts - non-current (2) — .5 .4 .1 .2 6.4 8.7 .3 Derivatives not Designated as Hedging Instruments Foreign currency forward contracts - current (1) .4 .9 2.6 .2 Total $ .6 $ 7.3 $ 11.3 $ .5 (1) Derivative assets and liabilities that have maturity dates equal to or less than 12 months from the respective balance sheet dates were included in other current assets and accrued liabilities and other, respectively, on our consolidated balance sheets. (2) Derivative assets and liabilities that have maturity dates greater than 12 months from the respective balance sheet dates were included in other assets and other liabilities, respectively, on our consolidated balance sheets. We utilize cash flow hedges to hedge forecasted foreign currency denominated transactions, primarily to reduce our exposure to foreign currency exchange rate risk associated with contract drilling expenses and capital expenditures denominated in various currencies. As of December 31, 2018 , we had cash flow hedges outstanding to exchange an aggregate $187.8 million for various foreign currencies, including $88.0 million for British pounds, $50.3 million for Australian dollars, $19.7 million for euros, $16.2 million for Brazilian reals, $11.0 million for Singapore dollars and $2.6 million for other currencies. Gains and losses, net of tax, on derivatives designated as cash flow hedges included in our consolidated statements of operations and comprehensive income for each of the years in the three-year period ended December 31, 2018 were as follows (in millions): Gain (Loss) Recognized in Other Comprehensive Income ("OCI") on Derivatives (Effective Portion) (Gain) Loss Reclassified from AOCI into Income (Effective Portion) (1) Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing) (2) 2018 2017 2016 2018 2017 2016 2018 2017 2016 Interest rate lock contracts (3) $ — $ — $ — $ .2 $ .2 $ .2 $ — $ — $ — Foreign currency forward contracts (4) (9.7 ) 8.5 (5.4 ) (1.2 ) .2 12.2 (1.9 ) (.7 ) 1.9 Total $ (9.7 ) $ 8.5 $ (5.4 ) $ (1.0 ) $ .4 $ 12.4 $ (1.9 ) $ (.7 ) $ 1.9 (1) Changes in the fair value of cash flow hedges are recorded in AOCI. Amounts recorded in AOCI associated with cash flow hedges are subsequently reclassified into contract drilling, depreciation or interest expense as earnings are affected by the underlying hedged forecasted transaction. (2) Gains and losses recognized in income for amounts excluded from effectiveness testing were included in other, net, in our consolidated statements of operations. (3) Losses on interest rate lock derivatives reclassified from AOCI into income were included in interest expense, net, in our consolidated statements of operations. (4) During the year ended December 31, 2018 , $400,000 of gains were reclassified from AOCI into contract drilling expense and $800,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2017 , $1.1 million of losses were reclassified from AOCI into contract drilling expense and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2016 , $13.1 million of losses were reclassified from AOCI into contract drilling and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. We have net assets and liabilities denominated in numerous foreign currencies and use various methods to manage our exposure to foreign currency exchange rate risk. We predominantly structure our drilling contracts in U.S. dollars, which significantly reduces the portion of our cash flows and assets denominated in foreign currencies. We occasionally enter into derivatives that hedge the fair value of recognized foreign currency denominated assets or liabilities but do not designate such derivatives as hedging instruments. In these situations, a natural hedging relationship generally exists whereby changes in the fair value of the derivatives offset changes in the fair value of the underlying hedged items. As of December 31, 2018 , we held derivatives not designated as hedging instruments to exchange an aggregate $175.7 million for various foreign currencies, including $89.3 million for euros, $19.8 million for Australian dollars, $19.6 million for Qatari riyals, $10.3 million for Indonesian rupiahs, $10.2 million for British pounds and $26.5 million for other currencies. Net losses of $11.8 million , gains of $10.0 million and losses of $7.0 million associated with our derivatives not designated as hedging instruments were included in other, net, in our consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 , respectively. As of December 31, 2018 , the estimated amount of net losses associated with derivatives, net of tax, that will be reclassified to earnings during the next 12 months was as follows (in millions): Net unrealized losses to be reclassified to contract drilling expense $ (5.2 ) Net realized gains to be reclassified to depreciation expense .8 Net realized losses to be reclassified to interest expense (.2 ) Net losses to be reclassified to earnings $ (4.6 )

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Shareholders' Equity	SHAREHOLDERS' EQUITY Activity in our various shareholders' equity accounts for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): Shares Par Value Additional Paid-in Capital Retained Earnings AOCI Treasury Shares Non-controlling Interest BALANCE, December 31, 2015 242.9 $ 24.4 $ 5,554.5 $ 985.3 $ 12.5 $ (63.8 ) $ 4.3 Net income — — — 890.2 — — 6.9 Dividends paid ($0.04 per share) — — — (11.4 ) — — — Distributions to noncontrolling interests — — — — — — (7.8 ) Equity issuance 65.6 6.5 579.0 — — — — Equity for debt exchange 1.8 .2 14.8 — — — — Equity component of convertible debt — — 220.0 — — — — Contributions from noncontrolling interests — — — — — — 1.0 Tax expense on share-based compensation — — (3.4 ) — — — — Repurchase of shares — — — — — (2.0 ) — Share-based compensation cost — — 37.3 — — — — Net other comprehensive loss — — — — 6.5 — — BALANCE, December 31, 2016 310.3 31.1 6,402.2 1,864.1 19.0 (65.8 ) 4.4 Net loss — — — (303.7 ) — — (.5 ) Dividends paid ($0.04 per share) — — — (13.6 ) — — — Cumulative-effect reduction from adoption of ASU 2016-16 — — — (14.1 ) — — — Distributions to noncontrolling interests — — — — — — (6.0 ) Equity issuance in connection with Atwood Merger 132.2 13.2 757.5 — — — — Shares issued under share-based compensation plans, net 4.5 .5 (.4 ) — — (1.3 ) — Repurchase of shares — — — — — (1.9 ) — Share-based compensation cost — — 35.7 — — — — Net other comprehensive income — — — — 9.6 — — BALANCE, December 31, 2017 447.0 44.8 7,195.0 1,532.7 28.6 (69.0 ) (2.1 ) Net loss — — — (639.7 ) — — 3.1 Dividends paid ($0.04 per share) — — — (18.0 ) — — — Cumulative-effect reduction from adoption of ASU 2018-02 — — — (.8 ) .8 — — Shares issued under share-based compensation plans, net 13.7 1.4 (.6 ) — — (1.3 ) — Distributions to noncontrolling interests — — — — — — (3.6 ) Repurchase of shares — — — — — (1.9 ) — Share-based compensation cost — — 30.6 — — — — Net other comprehensive income — — — — (11.2 ) — — BALANCE, December 31, 2018 460.7 $ 46.2 $ 7,225.0 $ 874.2 $ 18.2 $ (72.2 ) $ (2.6 ) In October 2017, as a result of the Atwood Merger, we issued 132.2 million of our Class A Ordinary shares, representing total equity consideration of $770.7 million based on a closing price of $5.83 per Class A ordinary share on October 5, 2017, the last trading day before the Merger Date. In April, 2016, we closed an underwritten public offering of 65,550,000 Class A ordinary shares at $9.25 per share. We received net proceeds from the offering of $585.5 million . In October 2016, we entered into a privately-negotiated exchange agreement whereby we issued 1,822,432 Class A ordinary shares, representing less than one percent of our outstanding Class A ordinary shares, in exchange for $24.5 million principal amount of our 2044 Notes, resulting in a pre-tax gain from debt extinguishment of $8.8 million . As a U.K. company governed in part by the Companies Act, we cannot issue new shares (other than in limited circumstances) without being authorized by our shareholders. At our 2018 annual general meeting, our shareholders authorized the allotment of 145.6 million Class A ordinary shares (or 291.2 million Class A ordinary shares in connection with an offer by way of a rights issue or other similar issue). This authority was further increased by shareholders at an additional general meeting on February 21, 2019, expiring at the next annual shareholder meeting or at the close of business on April 22, 2020 (whichever is earlier). Under English law, we are only able to declare dividends and return funds to our shareholders out of the accumulated distributable reserves on our statutory balance sheet. The declaration and amount of future dividends is at the discretion of our Board of Directors and will depend on our profitability, liquidity, financial condition, market outlook, reinvestment opportunities, capital requirements and other factors and restrictions our Board of Directors deems relevant. There can be no assurance that we will pay a dividend in the future. Our shareholders approved a new share repurchase program at our annual shareholder meeting held in May 2018. Subject to certain provisions under English law, including the requirement of Ensco plc to have sufficient distributable reserves, we may repurchase shares up to a maximum of $500.0 million in the aggregate from one or more financial intermediaries under the program, but in no case more than 65.0 million shares. The program terminates in May 2023. Our prior share repurchase program approved by our shareholders in 2013, under which we could repurchase up to a maximum of $2.0 billion in the aggregate, not to exceed 35.0 million shares, expired in May 2018. As of December 31, 2018 , there had been no share repurchases under this program.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Benefit Plans	BENEFIT PLANS In May 2018, our shareholders approved the 2018 Long-Term Incentive Plan (the "2018 LTIP") effective January 1, 2018, to provide for the issuance of non-vested share awards, share option awards and performance awards (collectively "awards"). The 2018 LTIP is similar to and replaces the Company's previously adopted 2012 Long-Term Incentive Plan (the “2012 LTIP”). No further awards will be granted under the 2012 LTIP. Under the 2018 LTIP, 59.0 million shares were reserved for issuance as awards to officers, non-employee directors and key employees who are in a position to contribute materially to our growth, development and long-term success. As of December 31, 2018 , there were 34.0 million shares available for issuance as awards under the 2018 LTIP. Awards may be satisfied by newly issued shares, including shares held by a subsidiary or affiliated entity, or by delivery of shares held in an affiliated employee benefit trust at the Company's discretion. In connection with the Atwood Merger, we assumed Atwood’s Amended and Restated 2007 Long-Term Incentive Plan (the “Atwood LTIP”) and the options outstanding thereunder. As of December 31, 2018 , there were 1.4 million shares remaining available for future issuance as awards under the Atwood LTIP, which may be granted to employees and other service providers who were not employed or engaged with Ensco prior to the Atwood Merger. Non-Vested Share Awards and Cash-Settled Awards Grants of share awards and share units (collectively "share awards") and share units to be settled in cash ("cash-settled awards"), generally vest at rates of 20% or 33% per year, as determined by a committee or subcommittee of the Board of Directors at the time of grant. During 2018 , we granted 114,000 cash-settled awards and 6.3 million share awards to our employees and non-employee directors pursuant to the 2018 LTIP. Our non-vested share awards have voting and dividend rights effective on the date of grant, and our non-vested share units have dividend rights effective on the date of grant. Compensation expense for share awards is measured at fair value on the date of grant and recognized on a straight-line basis over the requisite service period (usually the vesting period). Compensation expense for cash-settled awards is remeasured each quarter with a cumulative adjustment to compensation cost during the period based on changes in our share price. Our compensation cost is reduced for forfeited awards in the period in which the forfeitures occur. The following table summarizes share award and cash-settled award compensation expense recognized during each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Contract drilling $ 18.9 $ 18.3 $ 19.9 General and administrative 14.5 14.5 16.6 33.4 32.8 36.5 Tax benefit (2.8 ) (4.8 ) (5.9 ) Total $ 30.6 $ 28.0 $ 30.6 The following table summarizes the value of share awards and cash-settled awards granted and vested during each of the years in the three-year period ended December 31, 2018 : Share Awards Cash-Settled Awards 2018 2017 2016 2018 2017 2016 Weighted-average grant-date fair value of share awards granted (per share) $ 6.16 $ 7.90 $ 10.42 $ 5.31 $ 6.27 $ 9.64 Total fair value of share awards vested during the period (in millions) $ 7.5 $ 8.6 $ 8.8 $ 9.9 $ 3.9 $ — The following table summarizes share awards and cash-settled awards activity for the year ended December 31, 2018 (shares in thousands): Share Awards Cash-settled Awards Awards Weighted-Average Grant-Date Fair Value Awards Weighted-Average Grant-Date Fair Value Share awards and cash-settled awards as of December 31, 2017 3,305 $ 16.06 7,089 $ 7.37 Granted 6,298 6.16 114 5.31 Vested (1,312 ) 19.85 (1,512 ) 7.53 Forfeited (225 ) 11.62 (574 ) 7.18 Share awards and cash-settled awards as of December 31, 2018 8,066 $ 7.84 5,117 $ 7.30 As of December 31, 2018 , there was $63.5 million of total unrecognized compensation cost related to share awards, which is expected to be recognized over a weighted-average period of 3.5 years. Share Option Awards Share option awards ("options") granted to employees generally become exercisable in 25% increments over a four-year period or 33% increments over a three-year period and, to the extent not exercised, expire on either the seventh or tenth anniversary of the date of grant. The exercise price of options granted under the 2018 LTIP equals the market value of the underlying shares on the date of grant. As of December 31, 2018 , options granted to purchase 691,852 shares with a weighted-average exercise price of $25.46 were outstanding under the 2018 LTIP and predecessor or acquired plans. Excluding options assumed under the Atwood LTIP, no options have been granted since 2011, and there was no unrecognized compensation cost related to options as of December 31, 2018 . Performance Awards Under the 2018 LTIP, performance awards may be issued to our senior executive officers. Performance awards are subject to achievement of specified performance goals based on relative total shareholder return ("TSR") and relative return on capital employed ("ROCE") as compared to a specified peer group. The performance goals are determined by a committee or subcommittee of the Board of Directors. Awards are payable in either Ensco shares or cash upon attainment of relative TSR and ROCE performance goals. Performance awards granted during 2017 and 2018 are payable in cash while performance awards granted in 2016 are payable in Ensco shares. Performance awards generally vest at the end of a three -year measurement period based on attainment of performance goals. Our performance awards granted during 2016 are classified as equity awards and awards granted during 2017 and 2018 are classified as liability awards, all with compensation expense recognized over the requisite service period. The estimated probable outcome of attainment of the specified performance goals is based primarily on relative performance over the requisite performance period. Any subsequent changes in this estimate for the relative ROCE performance goal for the 2016 awards and both the ROCE and TSR performance goals for the 2017 and 2018 awards are recognized as a cumulative adjustment to compensation cost in the period in which the change in estimate occurs. The aggregate grant-date fair value of performance awards granted during 2018, 2017 and 2016 totaled $6.7 million , $6.7 million and $6.1 million , respectively. The aggregate fair value of performance awards vested during 2018, 2017 and 2016 totaled $0.7 million , $2.9 million and $2.8 million , respectively. During the years ended December 31, 2018, 2017 and 2016 , we recognized $8.2 million , $8.4 million and $3.1 million of compensation expense for performance awards, respectively, which was included in general and administrative expense in our consolidated statements of operations. As of December 31, 2018 , there was $10.3 million of total unrecognized compensation cost related to unvested performance awards, which is expected to be recognized over a weighted-average period of 1.9 years. Savings Plans We have savings plans, (the Ensco Savings Plan, the Ensco Multinational Savings Plan and the Ensco Limited Retirement Plan), which cover eligible employees as defined within each plan. The Ensco Savings Plan includes a 401(k) savings plan feature, which allows eligible employees to make tax-deferred contributions to the plan. The Ensco Limited Retirement Plan also allows eligible employees to make tax-deferred contributions to the plan. Contributions made to the Ensco Multinational Savings Plan may or may not qualify for tax deferral based on each plan participant's local tax requirements. We generally make matching cash contributions to the plans. We match 100% of the amount contributed by the employee up to a maximum of 5% of eligible salary. Matching contributions totaled $14.4 million , $12.2 million and $16.7 million for the years ended December 31, 2018, 2017 and 2016 , respectively. Any additional discretionary contributions made into the plans require approval of the Board of Directors and are generally paid in cash. We recorded an additional discretionary contribution provision of $19.2 million for the year ended December 31, 2016, which was paid during 2017. Matching contributions and additional discretionary contributions become vested in 33% increments upon completion of each initial year of service with all contributions becoming fully vested subsequent to achievement of three or more years of service. As of January 1, 2019, the plans were modified such that all previously paid employer contributions became 100% vested and any future employer contributions will vest immediately. We have 1.0 million shares reserved for issuance as matching contributions under the Ensco Savings Plan.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Taxes	INCOME TAXES We generated losses of $115.1 million , profits of $6.3 million and losses of $151.6 million from continuing operations before income taxes in the U.S. and losses of $423.8 million and $202.3 million and profits of $1.1 billion from continuing operations before income taxes in non-U.S. jurisdictions for the years ended December 31, 2018, 2017 and 2016 , respectively. The following table summarizes components of our provision for income taxes from continuing operations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Current income tax (benefit) expense: U.S. $ (19.9 ) $ (2.2 ) $ (6.6 ) Non-U.S. 52.9 56.4 86.4 33.0 54.2 79.8 Deferred income tax expense: U.S. 52.9 36.0 15.9 Non-U.S. 3.7 19.0 12.8 56.6 55.0 28.7 Total income tax expense $ 89.6 $ 109.2 $ 108.5 U.S. Tax Reform U.S. tax reform was enacted on December 22, 2017 and introduced significant changes to U.S. income tax law, including a reduction in the statutory income tax rate from 35% to 21% effective January 1, 2018, a one-time transition tax on deemed repatriation of deferred foreign income, a base erosion anti-abuse tax that effectively imposes a minimum tax on certain payments to non-U.S. affiliates, new and revised rules relating to the current taxation of certain income of foreign subsidiaries and revised rules associated with limitations on the deduction of interest. Due to the timing of the enactment of U.S. tax reform and the complexity involved in applying its provisions, we made reasonable estimates of its effects and recorded such amounts in our consolidated financial statements as of December 31, 2017 on a provisional basis. Throughout 2018, we continued to analyze applicable information and data, interpret rules and guidance issued by the U.S. Treasury Department and Internal Revenue Service, and make adjustments to the provisional amounts as provided for in Staff Accounting Bulletin No. 118. The U.S. Treasury Department is expected to continue finalizing rules associated with U.S. tax reform during 2019 and, when issued, these rules may have a material impact on our consolidated financial statements. During 2018, we recognized a tax benefit of $11.7 million associated with the one-time transition tax on deemed repatriation of the deferred foreign income of our U.S. subsidiaries. We recognized a net tax expense of $16.5 million during the fourth quarter of 2017 in connection with enactment of U.S. tax reform, consisting of a $38.5 million tax expense associated with the one-time transition tax on deemed repatriation of the deferred foreign income of our U.S. subsidiaries, a $17.3 million tax expense associated with revisions to rules over the taxation of income of foreign subsidiaries, a $20.0 million tax benefit resulting from the re-measurement of our deferred tax assets and liabilities as of December 31, 2017 to reflect the reduced tax rate and a $19.3 million tax benefit resulting from adjustments to the valuation allowance on deferred tax assets. Deferred Taxes The following table summarizes significant components of deferred income tax assets and liabilities as of December 31, 2018 and 2017 (in millions): 2018 2017 Deferred tax assets : Net operating loss carryforwards $ 148.4 $ 187.1 Foreign tax credits 123.6 132.3 Interest limitation carryforwards 40.2 — Premiums on long-term debt 23.8 36.1 Employee benefits, including share-based compensation 15.4 20.7 Deferred revenue 10.3 26.0 Other 14.5 12.8 Total deferred tax assets 376.2 415.0 Valuation allowance (316.0 ) (278.8 ) Net deferred tax assets 60.2 136.2 Deferred tax liabilities : Property and equipment (54.5 ) (51.5 ) Deferred U.S. tax on foreign income (31.5 ) (24.8 ) Deferred costs (5.3 ) (9.1 ) Deferred transition tax — (13.7 ) Other (3.7 ) (8.7 ) Total deferred tax liabilities (95.0 ) (107.8 ) Net deferred tax asset (liability) $ (34.8 ) $ 28.4 The realization of substantially all of our deferred tax assets is dependent upon generating sufficient taxable income during future periods in various jurisdictions in which we operate. Realization of certain of our deferred tax assets is not assured. We recognize a valuation allowance for deferred tax assets when it is more-likely-than-not that the benefit from the deferred tax asset will not be realized. The amount of deferred tax assets considered realizable could increase or decrease in the near-term if our estimates of future taxable income change. As of December 31, 2018 , we had deferred tax assets of $123.6 million for U.S. foreign tax credits (“FTCs”), $148.4 million related to $784.2 million of net operating loss (“NOL”) carryforwards and $40.2 million for U.S. interest limitation carryforwards, which can be used to reduce our income taxes payable in future years. The FTCs expire between 2022 and 2028 . NOL carryforwards, which were generated in various jurisdictions worldwide, include $449.8 million that do not expire and $334.4 million that will expire, if not utilized, between 2019 and 2037 . U.S. interest limitation carryforwards do not expire. Due to the uncertainty of realization, we have a $271.8 million valuation allowance on FTC, NOL carryforwards and U.S. interest limitation carryforwards. Effective Tax Rate Ensco plc, our parent company, is domiciled and resident in the U.K. Our subsidiaries conduct operations and earn income in numerous countries and are subject to the laws of taxing jurisdictions within those countries. The income of our non-U.K. subsidiaries is generally not subject to U.K. taxation. Income tax rates imposed in the tax jurisdictions in which our subsidiaries conduct operations vary, as does the tax base to which the rates are applied. In some cases, tax rates may be applicable to gross revenues, statutory or negotiated deemed profits or other bases utilized under local tax laws, rather than to net income. Our drilling rigs frequently move from one taxing jurisdiction to another to perform contract drilling services. In some instances, the movement of drilling rigs among taxing jurisdictions will involve the transfer of ownership of the drilling rigs among our subsidiaries. As a result of frequent changes in the taxing jurisdictions in which our drilling rigs are operated and/or owned, changes in profitability levels and changes in tax laws, our annual effective income tax rate may vary substantially from one reporting period to another. In periods of declining profitability, our income tax expense may not decline proportionally with income, which could result in higher effective income tax rates. Further, we may continue to incur income tax expense in periods in which we operate at a loss. Our consolidated effective income tax rate on continuing operations for each of the years in the three-year period ended December 31, 2018 , differs from the U.K. statutory income tax rate as follows: 2018 2017 2016 U.K. statutory income tax rate 19.0 % 19.2 % 20.0 % Non-U.K. taxes (18.0 ) (40.4 ) (7.9 ) Valuation allowance (16.9 ) (18.0 ) 2.6 Debt repurchases (1.6 ) (2.8 ) (4.1 ) Asset impairments (1.4 ) (17.1 ) — Bargain purchase gain (.2 ) 13.8 — U.S. tax reform 2.2 (8.4 ) — Tax restructuring transaction 1.7 — — Other (1.4 ) (2.0 ) .3 Effective income tax rate (16.6 )% (55.7 )% 10.9 % Our 2018 consolidated effective income tax rate includes the impact of various discrete tax items, including $46.0 million of tax benefit associated with the utilization of foreign tax credits subject to a valuation allowance, the transition tax on deemed repatriation of the deferred foreign income of our U.S. subsidiaries and a restructuring transaction, partially offset by $21.0 million of tax expense related to recovery of certain costs associated with an ongoing legal matter, repurchase and redemption of senior notes, unrecognized tax benefits associated with tax positions taken in prior years and rig sales. Our 2017 consolidated effective income tax rate includes $32.2 million associated with the impact of various discrete tax items, including $16.5 million of tax expense associated with U.S. tax reform and $15.7 million of tax expense associated with the exchange offers and debt repurchases, rig sales, a restructuring transaction, settlement of a previously disclosed legal contingency, the effective settlement of a liability for unrecognized tax benefits associated with a tax position taken in prior years and other resolutions of prior year tax matters. Our 2016 consolidated effective income tax rate includes the impact of various discrete tax items, including a $16.9 million tax expense resulting from net gains on the repurchase of various debt during the year, the recognition of an $8.4 million net tax benefit relating to the sale of various rigs, a $5.5 million tax benefit resulting from a net reduction in the valuation allowance on U.S. foreign tax credits and a net $5.3 million tax benefit associated with liabilities for unrecognized tax benefits and other adjustments relating to prior years. Excluding the impact of the aforementioned discrete tax items, our consolidated effective income tax rates for the years ended December 31, 2018 , 2017 and 2016 were (24.8)% , (96.0)% and 20.3% , The changes in our consolidated effective income tax rate, excluding discrete tax items, during the three-year period result primarily from U.S. tax reform and changes in the relative components of our earnings from the various taxing jurisdictions in which our drilling rigs are operated and/or owned and differences in tax rates in such taxing jurisdictions. Unrecognized Tax Benefits Our tax positions are evaluated for recognition using a more-likely-than-not threshold, and those tax positions requiring recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon effective settlement with a taxing authority that has full knowledge of all relevant information. As of December 31, 2018 , we had $143.0 million of unrecognized tax benefits, of which $136.5 million was included in other liabilities on our consolidated balance sheet and the remaining $6.5 million , which is associated with a tax position taken in tax years with NOL carryforwards, was presented as a reduction of deferred tax assets. As of December 31, 2017 , we had $147.6 million of unrecognized tax benefits, of which $139.4 million was included in other liabilities on our consolidated balance sheet and the remaining $8.2 million , which is associated with a tax position taken in tax years with NOL carryforwards, was presented as a reduction of deferred tax assets. If recognized, $127.4 million of the $143.0 million unrecognized tax benefits as of December 31, 2018 would impact our consolidated effective income tax rate. A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2018 and 2017 is as follows (in millions): 2018 2017 Balance, beginning of year $ 147.6 $ 122.0 Increases in unrecognized tax benefits as a result of tax positions taken during the current year 6.5 5.4 Impact of foreign currency exchange rates (5.0 ) 8.1 Lapse of applicable statutes of limitations (4.5 ) (.4 ) Increase in unrecognized tax benefits as a result of tax positions taken during prior years 2.5 .7 Decreases in unrecognized tax benefits as a result (3.8 ) (.2 ) Settlements with taxing authorities (.3 ) (10.2 ) Increases in unrecognized tax benefits as a result of the Atwood Merger — 22.2 Balance, end of year $ 143.0 $ 147.6 Accrued interest and penalties totaled $40.5 million and $38.6 million as of December 31, 2018 and 2017 , respectively, and were included in other liabilities on our consolidated balance sheets. We recognized a net expense of $1.9 million and $4.4 million and a net benefit of $3.8 million associated with interest and penalties during the years ended December 31, 2018, 2017 and 2016 , respectively. Interest and penalties are included in current income tax expense in our consolidated statements of operations. Our 2014 and subsequent years remain subject to examination for U.S. federal tax returns. Tax years as early as 2005 remain subject to examination in the other major tax jurisdictions in which we operated. Statutes of limitations applicable to certain of our tax positions lapsed during 2018, 2017 and 2016 , resulting in net income tax benefits, inclusive of interest and penalties, of $5.3 million , $1.1 million and $600,000 , respectively. Absent the commencement of examinations by tax authorities, statutes of limitations applicable to certain of our tax positions will lapse during 2019 . Therefore, it is reasonably possible that our unrecognized tax benefits will decline during the next 12 months by $500,000 , inclusive of $300,000 of accrued interest and penalties, all of which would impact our consolidated effective income tax rate if recognized. Intercompany Transfer of Drilling Rigs 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 consolidated balance sheet as of January 1, 2017. We did not recognize any income tax benefit or expense from the intercompany transfer of drilling rigs during the years ended December 31, 2018 and 2017, respectively. Undistributed Earnings Dividend income received by Ensco plc from its subsidiaries is exempt from U.K. taxation. We do not provide deferred taxes on undistributed earnings of certain subsidiaries because our policy and intention is to reinvest such earnings indefinitely. Each of the subsidiaries for which we maintain such policy has sufficient net assets, liquidity, contract backlog and/or other financial resources available to meet operational and capital investment requirements, which allows us to continue to maintain our policy of reinvesting the undistributed earnings indefinitely. As of December 31, 2018, the aggregate undistributed earnings of the subsidiaries for which we maintain a policy and intention to reinvest earnings indefinitely totaled $386.7 million . Should we make a distribution from these subsidiaries in the form of dividends or otherwise, we would be subject to additional income taxes. The unrecognized deferred tax liability related to these undistributed earnings was not practicable to estimate as of December 31, 2018.

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	DISCONTINUED OPERATIONS Our business strategy has been to focus on ultra-deepwater floater and premium jackup operations and de-emphasize other assets and operations that are not part of our long-term strategic plan or that no longer meet our standards for economic returns. Consistent with this strategy, we sold 12 jackup rigs, five dynamically positioned semisubmersible rigs, one moored semisubmersible rig and two drillships during the three-year period ended December 31, 2018 . We continue to focus on our fleet management strategy in light of the new composition of our rig fleet and will continue to review our fleet composition as we position Ensco for the future. As part of this strategy, we may act opportunistically from time to time to monetize assets to enhance shareholder value and improve our liquidity profile, in addition to selling or disposing of older, lower-specification or non-core rigs. Prior to 2015, individual rig disposals were classified as discontinued operations once the rigs met the criteria to be classified as held-for-sale. The operating results of the rigs through the date the rig was sold as well as the gain or loss on sale were included in results from discontinued operations, net, in our consolidated statement of operations. Net proceeds from the sales of the rigs were included in investing activities of discontinued operations in our consolidated statement of cash flows in the period in which the proceeds were received. During 2015, we adopted the Financial Accounting Standards Board’s Accounting Standards Update 2014-08, Presentation of Financial Statements ( Topic 205 ) and Property, Plant, and Equipment ( Topic 360 ): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (" Update 2014-08 "). Under the new guidance, only disposals representing a strategic shift in operations should be presented as discontinued operations. As a result, individual assets that are classified as held-for-sale beginning in 2015 are not reported as discontinued operations and their operating results and gain or loss on sale of these rigs are included in continuing operations in our consolidated statements of operations. Rigs that were classified as held-for-sale prior to 2015 continue to be reported as discontinued operations. The following rig sales were included in discontinued operations during the three-year period ended December 31, 2018 (in millions): Rig Date of Sale Segment (1) Net Proceeds Net Book Value (2) Pre-tax Gain (Loss) ENSCO 7500 April 2018 Floaters $ 2.6 $ 1.5 $ 1.1 ENSCO 90 June 2017 Jackups .3 .3 — ENSCO DS-2 May 2016 Floaters 5.0 4.0 1.0 ENSCO 58 April 2016 Jackups .7 .3 .4 ENSCO 6000 April 2016 Floaters .6 .8 (.2 ) $ 9.2 $ 6.9 $ 2.3 (1) The rigs' operating results were reclassified to discontinued operations in our consolidated statements of operations for each of the years in the three-year period ended December 31, 2018 and were previously included within the specified operating segment. (2) Includes the rig's net book value as well as inventory and other assets on the date of the sale. The following table summarizes income (loss) from discontinued operations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Revenues $ — $ — $ — Operating expenses 2.0 1.5 3.1 Operating loss (2.0 ) (1.5 ) (3.1 ) Income tax expense (benefit) 7.1 (2.1 ) (10.1 ) Gain on disposal of discontinued operations, net 1.0 .4 1.1 Income (loss) from discontinued operations $ (8.1 ) $ 1.0 $ 8.1 Income tax benefit from discontinued operations for the years ended December 31, 2018 , 2017 and 2016 included $6.9 million of discrete tax expense and $2.1 million and $10.2 million of discrete tax benefits, respectively. Debt and interest expense are not allocated to our discontinued operations.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES Leases We are obligated under leases for certain of our offices and equipment. Rental expense relating to operating leases was $40.1 million , $37.0 million and $39.7 million during the years ended December 31, 2018, 2017 and 2016 , respectively. Future minimum rental payments under our noncancellable operating lease obligations are as follows: $32.3 million during 2019 ; $18.7 million during 2020 ; $11.9 million during 2021 ; $9.2 million during 2022 ; $8.9 million during 2023 and $15.2 million thereafter. Capital Commitments The following table summarizes the cumulative amount of contractual payments made as of December 31, 2018 for our rigs under construction and estimated timing of our remaining contractual payments (in millions): Cumulative Paid (1) 2019 2020 Thereafter Total (2) ENSCO 123 (3) $ 276.4 $ 9.0 $ — $ — $ 285.4 ENSCO DS-14 (4) 15.0 — 165.0 — 180.0 ENSCO DS-13 (4) — 83.9 — — 83.9 $ 291.4 $ 92.9 $ 165.0 $ — $ 549.3 (1) Cumulative paid represents the aggregate amount of contractual payments made from commencement of the construction agreement through December 31, 2018 . Contractual payments made by Atwood prior to the Atwood Merger for ENSCO DS-13 and ENSCO DS-14 are excluded. (2) Total commitments are based on fixed-price shipyard construction contracts, exclusive of our internal costs associated with project management, commissioning and systems integration testing. Total commitments also exclude holding costs and interest. (3) In January 2018, we made a milestone payment of $207.4 million . The remaining unpaid balance of $9.0 million is due upon delivery. The $207.4 million milestone payment was invoiced and included in accounts payable - trade as of December 31, 2017 on our consolidated balance sheet. (4) The remaining milestone payments for ENSCO DS-13 and ENSCO DS-14 bear interest at a rate of 4.5% per annum, which accrues during the holding period until delivery. Delivery is scheduled for September 2019 and June 2020 for ENSCO DS-13 and ENSCO DS-14, respectively. Upon delivery, the remaining milestone payments and accrued interest thereon may be financed through a promissory note with the shipyard for each rig. The promissory notes will bear interest at a rate of 5.0% per annum with a maturity date of December 30, 2022 and will be secured by a mortgage on each respective rig. The remaining milestone payments for ENSCO DS-13 and ENSCO DS-14 are included in the table above in the period in which we expect to take delivery of the rig. However, we may elect to execute the promissory notes and defer payment until December 2022. The actual timing of these expenditures may vary based on the completion of various construction milestones, which are, to a large extent, beyond our control. DSA Dispute On January 4, 2016, Petrobras sent a notice to us declaring the drilling services agreement with Petrobras (the "DSA") for ENSCO DS-5, a drillship ordered from Samsung Heavy Industries, a shipyard in South Korea ("SHI"), void effective immediately, reserving its rights and stating its intention to seek any restitution to which it may be entitled. The previously disclosed arbitral hearing on liability related to the matter was held in March 2018. Prior to the arbitration tribunal issuing its decision, we and Petrobras agreed in August 2018 to a settlement of all claims relating to the DSA. No payments were made by either party in connection with the settlement agreement. The parties agreed to normalize business relations and the settlement agreement provides for our participation in current and future Petrobras tenders on the same basis as all other companies invited to these tenders. No losses were recognized during 2018 with respect to this settlement as all disputed receivables with Petrobras related to the DSA were fully reserved in 2015. See Item 3 “Legal Proceedings” in our quarterly report on Form 10-Q for the quarter ended June 30, 2018 for further information about the DSA dispute. In November 2016, we initiated separate arbitration proceedings in the U.K. against SHI for the losses incurred in connection with the foregoing Petrobras arbitration and certain other losses relating to the DSA. SHI subsequently filed a statement of defense disputing our claim. In January 2018, the arbitration tribunal for the SHI matter issued an award on liability fully in our favor. In August 2018, the tribunal awarded us approximately $2.8 million in costs and legal fees incurred to date, plus interest, which was collected during the fourth quarter. The January 2018 arbitration award provides that SHI is liable to us for $10 million or damages that we can prove. We have submitted to the tribunal our claim for damages. The arbitral hearing on damages owed to us by SHI is scheduled to take place in the first quarter of 2019. We are unable to estimate the ultimate outcome of recovery for damages at this time. Other Matters In addition to the foregoing, we are named defendants or parties in certain other lawsuits, claims or proceedings incidental to our business and are involved from time to time as parties to governmental investigations or proceedings, including matters related to taxation, arising in the ordinary course of business. Although the outcome of such lawsuits or other proceedings cannot be predicted with certainty and the amount of any liability that could arise with respect to such lawsuits or other proceedings cannot be predicted accurately, we do not expect these matters to have a material adverse effect on our financial position, operating results and cash flows. In the ordinary course of business with customers and others, we have entered into letters of credit to guarantee our performance as it relates to our drilling contracts, contract bidding, customs duties, tax appeals and other obligations in various jurisdictions. Letters of credit outstanding as of December 31, 2018 totaled $126.3 million and are issued under facilities provided by various banks and other financial institutions. Obligations under these letters of credit and surety bonds are not normally called, as we typically comply with the underlying performance requirement. As of December 31, 2018 , we had not been required to make collateral deposits with respect to these agreements.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Segment Information	SEGMENT INFORMATION Our business consists of three operating segments: (1) Floaters, which includes our drillships and semisubmersible rigs, (2) Jackups and (3) Other, which consists of management services on rigs owned by third-parties. Our two reportable segments, Floaters and Jackups, provide one service, contract drilling. Segment information for each of the years in the three-year period ended December 31, 2018 is presented below (in millions). General and administrative expense and depreciation expense incurred by our corporate office are not allocated to our operating segments for purposes of measuring segment operating income and were included in "Reconciling Items." We measure segment assets as property and equipment. Year Ended December 31, 2018 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,013.5 $ 630.9 $ 61.0 $ 1,705.4 $ — $ 1,705.4 Operating expenses Contract drilling (exclusive of depreciation) 737.4 526.5 55.5 1,319.4 — 1,319.4 Loss on impairment — 40.3 — 40.3 — 40.3 Depreciation 311.8 153.3 — 465.1 13.8 478.9 General and administrative — — — — 102.7 102.7 Operating income (loss) $ (35.7 ) $ (89.2 ) $ 5.5 $ (119.4 ) $ (116.5 ) $ (235.9 ) Property and equipment, net $ 9,465.6 $ 3,114.1 $ — $ 12,579.7 $ 36.5 $ 12,616.2 Capital expenditures $ 105.5 $ 317.7 $ — $ 423.2 $ 3.5 $ 426.7 Year Ended December 31, 2017 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,143.5 $ 640.3 $ 59.2 $ 1,843.0 $ — $ 1,843.0 Operating expenses Contract drilling (exclusive of depreciation) 624.2 512.1 53.2 1,189.5 — 1,189.5 Loss on impairment 174.7 8.2 — 182.9 — 182.9 Depreciation 297.4 131.5 — 428.9 15.9 444.8 General and administrative — — — — 157.8 157.8 Operating income (loss) $ 47.2 $ (11.5 ) $ 6.0 $ 41.7 $ (173.7 ) $ (132.0 ) Property and equipment, net $ 9,650.9 $ 3,177.6 $ — $ 12,828.5 $ 45.2 $ 12,873.7 Capital expenditures $ 470.3 $ 62.1 $ — $ 532.4 $ 4.3 $ 536.7 Year Ended December 31, 2016 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,771.1 $ 929.5 $ 75.8 $ 2,776.4 $ — $ 2,776.4 Operating expenses Contract drilling (exclusive of depreciation) 725.0 516.8 59.2 1,301.0 — 1,301.0 Depreciation 304.1 123.7 — 427.8 17.5 445.3 General and administrative — — — — 100.8 100.8 Operating income $ 742.0 $ 289.0 $ 16.6 $ 1,047.6 $ (118.3 ) $ 929.3 Property and equipment, net $ 8,300.4 $ 2,561.0 $ — $ 10,861.4 $ 57.9 $ 10,919.3 Capital expenditures $ 110.3 $ 206.2 $ — $ 316.5 $ 5.7 $ 322.2 Information about Geographic Areas As of December 31, 2018 , our Floaters segment consisted of 10 drillships, nine dynamically positioned semisubmersible rigs and three moored semisubmersible rigs deployed in various locations. Additionally, our Floaters segment included two ultra-deepwater drillships under construction in South Korea. Our Jackups segment consisted of 35 jackup rigs, of which 34 were deployed in various locations and one was under construction in Singapore. As of December 31, 2018 , the geographic distribution of our drilling rigs by operating segment was as follows: Floaters Jackups Total North & South America 8 4 12 Europe & the Mediterranean 7 11 18 Middle East & Africa 3 12 15 Asia & Pacific Rim 4 7 11 Asia & Pacific Rim (under construction) 2 1 3 Total 24 35 59 We provide management services on two rigs owned by third-parties not included in the table above. For purposes of our long-lived asset geographic disclosure, we attribute assets to the geographic location of the drilling rig as of the end of the applicable year. For new construction projects, assets are attributed to the location of future operation if known or to the location of construction if the ultimate location of operation is undetermined. Information by country for those countries that account for more than 10% of our long-lived assets as well as the United Kingdom, our country of domicile, was as follows (in millions): Long-lived Assets 2018 2017 2016 Spain $ 2,306.6 $ 2,004.2 $ 2,334.5 United States 2,270.0 2,764.9 2,898.3 Nigeria 1,368.2 583.3 — United Kingdom 1,185.2 609.4 409.0 Singapore 23.9 2,859.3 1,388.4 Other countries 5,462.3 4,052.6 3,889.1 Total $ 12,616.2 $ 12,873.7 $ 10,919.3

Supplemental Financial Informat

Supplemental Financial Information	12 Months Ended
	Dec. 31, 2018
Supplemental Financial Information [Abstract]
Supplemental Balance Sheet Disclosures [Text Block]	. SUPPLEMENTAL FINANCIAL INFORMATION Consolidated Balance Sheet Information Accounts receivable, net, as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Trade (1) $ 301.7 $ 335.4 Other 46.4 33.6 348.1 369.0 Allowance for doubtful accounts (1) (3.4 ) (23.6 ) $ 344.7 $ 345.4 (1) The decline in trade receivables and allowance for doubtful accounts is primarily due to the settlement with Petrobras described in "Note 12 - Commitments and Contingencies". Other current assets as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Inventory $ 268.1 $ 278.8 Prepaid taxes 35.0 43.5 Deferred costs 23.5 29.7 Prepaid expenses 15.2 14.2 Other 19.1 15.0 $ 360.9 $ 381.2 Other assets as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Deferred tax assets $ 29.4 $ 38.8 Supplemental executive retirement plan assets 27.2 30.9 Deferred costs 21.5 37.4 Intangible assets 2.5 15.7 Other 17.2 17.4 $ 97.8 $ 140.2 Accrued liabilities and other as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Accrued interest $ 100.6 $ 83.1 Personnel costs 82.5 112.0 Deferred revenue 56.9 71.9 Income and other taxes payable 36.9 46.4 Derivative liabilities 10.9 .4 Other 30.2 12.1 $ 318.0 $ 325.9 Other liabilities as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Unrecognized tax benefits (inclusive of interest and penalties) $ 177.0 $ 178.0 Deferred tax liabilities 70.7 18.5 Intangible liabilities 53.5 59.6 Supplemental executive retirement plan liabilities 28.1 32.0 Personnel costs 25.1 18.1 Deferred revenue 20.5 51.2 Deferred rent 11.7 17.1 Other 9.4 12.2 $ 396.0 $ 386.7 Accumulated other comprehensive income as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Derivative instruments $ 12.6 $ 22.5 Currency translation adjustment 7.3 7.8 Other (1.7 ) (1.7 ) $ 18.2 $ 28.6 Consolidated Statement of Operations Information Repair and maintenance expense related to continuing operations for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 Repair and maintenance expense $ 198.4 $ 188.7 $ 151.1 Consolidated Statement of Cash Flows Information Net cash provided by (used in) operating activities of continuing operations attributable to the net change in operating assets and liabilities for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 (Increase) decrease in accounts receivable $ (6.2 ) $ 83.2 $ 222.4 (Increase) decrease in other assets (2.8 ) (14.0 ) 44.0 Decrease in liabilities (9.0 ) (3.8 ) (125.8 ) $ (18.0 ) $ 65.4 $ 140.6 During periods in which our business contracts, resulting in significantly lower revenues and expenses as compared to the prior year, we typically generate positive cash flows from the net change in operating assets and liabilities as the impact from the collection of receivables that were accrued during the prior period is generally larger than the impact from the payment of expenses incurred in the prior period. For the years ended December 31, 2017 and 2016, our business contracted significantly as compared to the respective prior year periods resulting in positive cash generated from the net change in operating assets and liabilities. During the year ended December 31, 2018, our business contracted at a more moderate pace, resulting in modest negative cash flows from the net change in operating assets and liabilities. Cash paid for interest and income taxes for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 Interest, net of amounts capitalized $ 232.6 $ 199.8 $ 264.8 Income taxes 58.4 62.8 56.4 Capitalized interest totaled $62.6 million , $72.5 million and $45.7 million during the years ended December 31, 2018, 2017 and 2016 , respectively. Capital expenditure accruals totaling $27.8 million , $234.3 million and $11.5 million for the years ended December 31, 2018, 2017 and 2016 , respectively, were excluded from investing activities in our consolidated statements of cash flows. In January 2018, we made a $207.4 million milestone payment for ENSCO 123 and the remaining unpaid balance of $9.0 million is due upon delivery. The $207.4 million milestone payment was invoiced and included in accounts payable - trade as of December 31, 2017 on our consolidated balance sheet. Amortization, net, includes amortization of deferred mobilization revenues and costs, deferred capital upgrade revenues, intangible amortization and other amortization. Other includes amortization of debt discounts and premiums, deferred financing costs, deferred charges for income taxes incurred on intercompany transfers of drilling rigs and other items. Concentration of Risk We are exposed to credit risk relating to our receivables from customers, our cash and cash equivalents, investments and our use of derivatives in connection with the management of foreign currency exchange rate risk. We mitigate our credit risk relating to receivables from customers, which consist primarily of major international, government-owned and independent oil and gas companies, by performing ongoing credit evaluations. We also maintain reserves for potential credit losses, which generally have been within our expectations. We mitigate our credit risk relating to cash and investments by focusing on diversification and quality of instruments. Short-term investments consist of a portfolio of time deposits held with several well-capitalized financial institutions, and we monitor the financial condition of those financial institutions. We mitigate our credit risk relating to counterparties of our derivatives through a variety of techniques, including transacting with multiple, high-quality financial institutions, thereby limiting our exposure to individual counterparties and by entering into ISDA Master Agreements, which include provisions for a legally enforceable master netting agreement, with our derivative counterparties. See "Note 7 - Derivative Instruments" for additional information on our derivative activity. The terms of the ISDA agreements may also include credit support requirements, cross default provisions, termination events or set-off provisions. Legally enforceable master netting agreements reduce credit risk by providing protection in bankruptcy in certain circumstances and generally permitting the closeout and netting of transactions with the same counterparty upon the occurrence of certain events. Consolidated revenues by customer for the years ended December 31, 2018 , 2017 and 2016 were as follows: 2018 2017 2016 Total (1) 15 % 22 % 13 % Saudi Aramco (2) 11 % 9 % 6 % Petrobras (1) 8 % 11 % 9 % BP (3) 7 % 15 % 12 % Other 59 % 43 % 60 % 100 % 100 % 100 % (1) For the years ended December 31, 2018, 2017 and 2016 , all Total and Petrobras revenues were attributable to the Floater segment. (2) For the years ended December 31, 2018, 2017 and 2016 , all Saudi Aramco revenues were attributable to the Jackup segment. (3) For the year ended December 31, 2018, 27% , 53% and 20% of BP revenues were attributable to our Floater, Other and Jackup segments, respectively. For the year ended December 31, 2017, 78% of BP revenues were attributable to our Floater segment and the remaining revenues were attributable to our Other segment. For the year ended December 31, 2016, 76% , 17% and 7% of BP revenues were attributable to our Floater, Other and Jackup segments, respectively. For purposes of our geographic disclosure, we attribute revenues to the geographic location where such revenues are earned. Consolidated revenues by region, including the United Kingdom, our country of domicile, for the years ended December 31, 2018, 2017 and 2016 were as follows (in millions): 2018 2017 2016 Angola (1) $ 285.7 $ 445.7 $ 552.1 Australia (2) 283.9 206.7 222.8 U.S. Gulf of Mexico (3) 214.7 149.8 531.7 United Kingdom (4) 192.6 164.6 246.2 Saudi Arabia (4) 182.2 171.8 210.6 Brazil (5) 139.6 196.2 298.0 Egypt (5) 31.2 214.8 141.2 Other 375.5 293.4 573.8 $ 1,705.4 $ 1,843.0 $ 2,776.4 (1) For the years ended December 31, 2018, 2017 and 2016 , 86% , 88% and 87% of revenues earned in Angola, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment. (2) For the years ended December 31, 2018, 2017 and 2016 , 92% , 87% and 95% of revenues earned in Australia, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment. (3) For the years ended December 31, 2018, 2017 and 2016 , 30% , 29% and 82% of revenues earned in the U.S. Gulf of Mexico, respectively, were attributable to our Floaters segment, 42% , 31% and 7% of revenues were attributable to our Jackup segment, respectively, and the remaining revenues were attributable to our Other segment, respectively. (4) For the years ended December 31, 2018, 2017 and 2016 , all revenues were attributable to our Jackup segment. (5) For the years ended December 31, 2018, 2017 and 2016 , all revenues were attributable to our Floater segment.

Guarantee Of Registered Securit

Guarantee Of Registered Securities	12 Months Ended
	Dec. 31, 2018
Guarantees [Abstract]
Guarantee Of Registered Securities	GUARANTEE OF REGISTERED SECURITIES In connection with the Pride acquisition, Ensco plc and Pride entered into a supplemental indenture to the indenture dated as of July 1, 2004 between Pride and the Bank of New York Mellon, as indenture trustee, providing for, among other matters, the full and unconditional guarantee by Ensco plc of Pride’s 6.875% senior notes due 2020 and 7.875% senior notes due 2040 , which had an aggregate outstanding principal balance of $ 422.9 million as of December 31, 2018 . The Ensco plc guarantee provides for the unconditional and irrevocable guarantee of the prompt payment, when due, of any amount owed to the holders of the notes. Ensco plc is also a full and unconditional guarantor of the 7.2% Debentures due 2027 issued by Ensco International Incorporated in November 1997, which had an aggregate outstanding principal balance of $150.0 million as of December 31, 2018 . Pride (formerly Pride International, Inc.) and Ensco International Incorporated are 100% owned subsidiaries of Ensco plc. All guarantees are unsecured obligations of Ensco plc ranking equal in right of payment with all of its existing and future unsecured and unsubordinated indebtedness. The following tables present our condensed consolidating statements of operations for each of the years in the three-year period ended December 31, 2018 ; our condensed consolidating statements of comprehensive income (loss) for each of the years in the three-year period ended December 31, 2018 ; our condensed consolidating balance sheets as of December 31, 2018 and 2017 ; and our condensed consolidating statements of cash flows for each of the years in the three-year period ended December 31, 2018 , in accordance with Rule 3-10 of Regulation S-X. ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 49.5 $ 155.2 $ — $ 1,802.8 $ (302.1 ) $ 1,705.4 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 51.0 139.5 — 1,431.0 (302.1 ) 1,319.4 Loss on impairment — — — 40.3 — 40.3 Depreciation — 14.2 — 464.7 — 478.9 General and administrative 46.3 .4 — 56.0 — 102.7 OPERATING INCOME (LOSS) (47.8 ) 1.1 — (189.2 ) — (235.9 ) OTHER INCOME (EXPENSE), NET 2.7 (135.2 ) (89.0 ) (109.0 ) 27.5 (303.0 ) LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES (45.1 ) (134.1 ) (89.0 ) (298.2 ) 27.5 (538.9 ) INCOME TAX EXPENSE — 43.3 — 46.3 — 89.6 DISCONTINUED OPERATIONS, NET — — — (8.1 ) — (8.1 ) EQUITY EARNINGS (LOSSES) IN AFFILIATES, NET OF TAX (594.6 ) 121.8 93.3 — 379.5 — NET INCOME (LOSS) (639.7 ) (55.6 ) 4.3 (352.6 ) 407.0 (636.6 ) NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (3.1 ) — (3.1 ) NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (639.7 ) $ (55.6 ) $ 4.3 $ (355.7 ) $ 407.0 $ (639.7 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 52.9 $ 163.3 $ — $ 1,941.2 $ (314.4 ) $ 1,843.0 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 50.0 149.9 — 1,304.0 (314.4 ) 1,189.5 Loss on impairment — — — 182.9 — 182.9 Depreciation — 15.9 — 428.9 — 444.8 General and administrative 45.4 50.8 — 61.6 — 157.8 OPERATING LOSS (42.5 ) (53.3 ) — (36.2 ) — (132.0 ) OTHER INCOME (EXPENSE), NET (6.8 ) (110.5 ) (71.7 ) 110.5 14.5 (64.0 ) INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES (49.3 ) (163.8 ) (71.7 ) 74.3 14.5 (196.0 ) INCOME TAX EXPENSE — 45.0 — 64.2 — 109.2 DISCONTINUED OPERATIONS, NET — — — 1.0 — 1.0 EQUITY EARNINGS (LOSSES) IN AFFILIATES, NET OF TAX (254.4 ) 129.6 84.2 — 40.6 — NET INCOME (LOSS) (303.7 ) (79.2 ) 12.5 11.1 55.1 (304.2 ) NET LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — .5 — .5 NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (303.7 ) $ (79.2 ) $ 12.5 $ 11.6 $ 55.1 $ (303.7 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 27.9 $ 144.4 $ — $ 2,897.4 $ (293.3 ) $ 2,776.4 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 27.3 144.8 .1 1,422.1 (293.3 ) 1,301.0 Depreciation — 17.2 .4 427.7 — 445.3 General and administrative 36.2 .2 — 64.4 — 100.8 OPERATING INCOME (LOSS) (35.6 ) (17.8 ) (0.5 ) 983.2 — 929.3 OTHER INCOME (EXPENSE), NET 152.9 (79.0 ) (76.6 ) 7.8 63.1 68.2 INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 117.3 (96.8 ) (77.1 ) 991.0 63.1 997.5 INCOME TAX EXPENSE (BENEFIT) — .7 (.6 ) 108.4 — 108.5 DISCONTINUED OPERATIONS, NET — — — 8.1 — 8.1 EQUITY EARNINGS IN AFFILIATES, NET OF TAX 772.9 205.7 125.7 — (1,104.3 ) — NET INCOME 890.2 108.2 49.2 890.7 (1,041.2 ) 897.1 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (6.9 ) — (6.9 ) NET INCOME ATTRIBUTABLE TO ENSCO $ 890.2 $ 108.2 $ 49.2 $ 883.8 $ (1,041.2 ) $ 890.2 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME (LOSS) $ (639.7 ) $ (55.6 ) $ 4.3 $ (352.6 ) $ 407.0 $ (636.6 ) OTHER COMPREHENSIVE LOSS, NET Net change in fair value of derivatives — (9.7 ) — — — (9.7 ) Reclassification of net gains on derivative instruments from other comprehensive loss into net loss — (1.0 ) — — — (1.0 ) Other — — — (.5 ) — (.5 ) NET OTHER COMPREHENSIVE LOSS — (10.7 ) — (.5 ) — (11.2 ) COMPREHENSIVE INCOME (LOSS) (639.7 ) (66.3 ) 4.3 (353.1 ) 407.0 (647.8 ) COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (3.1 ) — (3.1 ) COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (639.7 ) $ (66.3 ) $ 4.3 $ (356.2 ) $ 407.0 $ (650.9 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME (LOSS) $ (303.7 ) $ (79.2 ) $ 12.5 $ 11.1 $ 55.1 $ (304.2 ) OTHER COMPREHENSIVE INCOME, NET Net change in fair value of derivatives — 8.5 — — — 8.5 Reclassification of net losses on derivative instruments from other comprehensive income into net income — .4 — — — .4 Other — — — .7 — .7 NET OTHER COMPREHENSIVE INCOME — 8.9 — .7 — 9.6 COMPREHENSIVE INCOME (LOSS) (303.7 ) (70.3 ) 12.5 11.8 55.1 (294.6 ) COMPREHENSIVE LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — .5 — .5 COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (303.7 ) $ (70.3 ) $ 12.5 $ 12.3 $ 55.1 $ (294.1 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME $ 890.2 $ 108.2 $ 49.2 $ 890.7 $ (1,041.2 ) $ 897.1 OTHER COMPREHENSIVE INCOME (LOSS), NET Net change in fair value of derivatives — (5.4 ) — — — (5.4 ) Reclassification of net gains on derivative instruments from other comprehensive income into net loss — 12.4 — — — 12.4 Other — — — (.5 ) — (.5 ) NET OTHER COMPREHENSIVE INCOME (LOSS) — 7.0 — (.5 ) — 6.5 COMPREHENSIVE INCOME 890.2 115.2 49.2 890.2 (1,041.2 ) 903.6 COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (6.9 ) — (6.9 ) COMPREHENSIVE INCOME ATTRIBUTABLE TO ENSCO $ 890.2 $ 115.2 $ 49.2 $ 883.3 $ (1,041.2 ) $ 896.7 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total ASSETS CURRENT ASSETS Cash and cash equivalents $ 199.8 $ — $ 2.7 $ 72.6 $ — $ 275.1 Short-term investments 329.0 — — — — 329.0 Accounts receivable, net 7.3 25.4 — 312.0 — 344.7 Accounts receivable from affiliates 1,861.2 171.4 — 131.7 (2,164.3 ) — Other .6 6.0 — 354.3 — 360.9 Total current assets 2,397.9 202.8 2.7 870.6 (2,164.3 ) 1,309.7 PROPERTY AND EQUIPMENT, AT COST 1.8 125.2 — 15,390.0 — 15,517.0 Less accumulated depreciation 1.8 91.3 — 2,807.7 — 2,900.8 Property and equipment, net — 33.9 — 12,582.3 — 12,616.2 DUE FROM AFFILIATES 2,413.8 234.5 125.0 2,715.1 (5,488.4 ) — INVESTMENTS IN AFFILIATES 8,522.6 3,713.7 1,199.9 — (13,436.2 ) — OTHER ASSETS 8.1 — — 89.7 — 97.8 $ 13,342.4 $ 4,184.9 $ 1,327.6 $ 16,257.7 $ (21,088.9 ) $ 14,023.7 LIABILITIES AND SHAREHOLDERS' EQUITY CURRENT LIABILITIES Accounts payable and accrued liabilities $ 85.3 $ 32.0 $ 12.7 $ 398.5 $ — $ 528.5 Accounts payable to affiliates 59.7 139.5 38.2 1,926.9 (2,164.3 ) — Total current liabilities 145.0 171.5 50.9 2,325.4 (2,164.3 ) 528.5 DUE TO AFFILIATES 1,432.0 1,226.9 1,366.5 1,463.0 (5,488.4 ) — LONG-TERM DEBT 3,676.5 149.3 502.6 682.0 — 5,010.4 OTHER LIABILITIES .1 64.3 — 331.6 — 396.0 ENSCO SHAREHOLDERS' EQUITY (DEFICIT) 8,088.8 2,572.9 (592.4 ) 11,458.3 (13,436.2 ) 8,091.4 NONCONTROLLING INTERESTS — — — (2.6 ) — (2.6 ) Total equity (deficit) 8,088.8 2,572.9 (592.4 ) 11,455.7 (13,436.2 ) 8,088.8 $ 13,342.4 $ 4,184.9 $ 1,327.6 $ 16,257.7 $ (21,088.9 ) $ 14,023.7 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total ASSETS CURRENT ASSETS Cash and cash equivalents $ 185.2 $ — $ 25.6 $ 234.6 $ — $ 445.4 Short-term investments 440.0 — — — — 440.0 Accounts receivable, net 6.9 .4 — 338.1 — 345.4 Accounts receivable from affiliates 351.8 492.7 — 424.3 (1,268.8 ) — Other — 8.8 — 372.4 — 381.2 Total current assets 983.9 501.9 25.6 1,369.4 (1,268.8 ) 1,612.0 PROPERTY AND EQUIPMENT, AT COST 1.8 120.8 — 15,209.5 — 15,332.1 Less accumulated depreciation 1.8 77.1 — 2,379.5 — 2,458.4 Property and equipment, net — 43.7 — 12,830.0 — 12,873.7 DUE FROM AFFILIATES 3,002.1 2,618.0 165.1 3,736.1 (9,521.3 ) — INVESTMENTS IN AFFILIATES 9,098.5 3,591.9 1,106.6 — (13,797.0 ) — OTHER ASSETS 12.9 5.0 — 226.5 (104.2 ) 140.2 $ 13,097.4 $ 6,760.5 $ 1,297.3 $ 18,162.0 $ (24,691.3 ) $ 14,625.9 LIABILITIES AND SHAREHOLDERS' EQUITY CURRENT LIABILITIES Accounts payable and accrued liabilities $ 55.4 $ 39.0 $ 21.7 $ 642.4 $ — $ 758.5 Accounts payable to affiliates 67.3 458.3 12.4 730.8 (1,268.8 ) — Total current liabilities 122.7 497.3 34.1 1,373.2 (1,268.8 ) 758.5 DUE TO AFFILIATES 1,402.9 3,559.2 753.9 3,805.3 (9,521.3 ) — LONG-TERM DEBT 2,841.8 149.2 1,106.0 653.7 — 4,750.7 OTHER LIABILITIES — 3.1 — 487.8 (104.2 ) 386.7 ENSCO SHAREHOLDERS' EQUITY (DEFICIT) 8,730.0 2,551.7 (596.7 ) 11,844.1 (13,797.0 ) 8,732.1 NONCONTROLLING INTERESTS — — — (2.1 ) — (2.1 ) Total equity (deficit) 8,730.0 2,551.7 (596.7 ) 11,842.0 (13,797.0 ) 8,730.0 $ 13,097.4 $ 6,760.5 $ 1,297.3 $ 18,162.0 $ (24,691.3 ) $ 14,625.9 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ 18.1 $ (135.1 ) $ (97.6 ) $ 158.9 $ — $ (55.7 ) INVESTING ACTIVITIES Maturities of short-term investments 1,030.0 — — — — 1,030.0 Purchases of short-term investments (919.0 ) — — — — (919.0 ) Purchase of affiliate debt (551.7 ) — — — 551.7 — Sale of affiliate debt 479.0 — — — (479.0 ) — Additions to property and equipment — — — (426.7 ) — (426.7 ) Net proceeds from disposition of assets — — 11.0 — 11.0 Net cash provided by (used in) investing activities of continuing operations 38.3 — — (415.7 ) 72.7 (304.7 ) FINANCING ACTIVITIES Proceeds from issuance of senior notes 1,000.0 — — — — 1,000.0 Advances from (to) affiliates (845.0 ) 135.1 612.5 97.4 — — Reduction of long-term borrowings (159.9 ) — (537.8 ) (0.8 ) (72.7 ) (771.2 ) Cash dividends paid (17.9 ) — — — — (17.9 ) Debt issuance costs (17.0 ) — — — — (17.0 ) Other (2.0 ) — — (3.7 ) — (5.7 ) Net cash provided by (used in) financing activities (41.8 ) 135.1 74.7 92.9 (72.7 ) 188.2 Net cash provided by discontinued operations — — — 2.5 — 2.5 Effect of exchange rate changes on cash and cash equivalents — — — (.6 ) — (.6 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 14.6 — (22.9 ) (162.0 ) — (170.3 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 185.2 — 25.6 234.6 — 445.4 CASH AND CASH EQUIVALENTS, END OF YEAR $ 199.8 $ — $ 2.7 $ 72.6 $ — $ 275.1 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ (18.2 ) $ (117.6 ) $ (100.1 ) $ 495.3 $ — $ 259.4 INVESTING ACTIVITIES Purchases of short-term investments (1,022.9 ) — — (17.1 ) — (1,040.0 ) Maturities of short-term investments 1,748.0 5.5 — 289.0 — 2,042.5 Additions to property and equipment — — — (536.7 ) — (536.7 ) Net proceeds from disposition of assets — — — 2.8 — 2.8 Purchase of affiliate debt (316.3 ) — — — 316.3 — Acquisition of Atwood, net of cash acquired — — — (871.6 ) — (871.6 ) Net cash provided by (used in) investing activities of continuing operations 408.8 5.5 — (1,133.6 ) 316.3 (403.0 ) FINANCING ACTIVITIES Reduction of long-term borrowings (220.7 ) — — — (316.3 ) (537.0 ) Debt issuance costs (12.0 ) — — — — (12.0 ) Cash dividends paid (13.8 ) — — — — (13.8 ) Advances from (to) affiliates (848.9 ) 112.1 105.9 630.9 — — Other (2.6 ) — — (5.1 ) — (7.7 ) Net cash provided by (used in) financing activities (1,098.0 ) 112.1 105.9 625.8 (316.3 ) (570.5 ) Net cash used in discontinued operations — — — (.8 ) — (.8 ) Effect of exchange rate changes on cash and cash equivalents — — — .6 — .6 NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS (707.4 ) — 5.8 (12.7 ) — (714.3 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 892.6 — 19.8 247.3 — 1,159.7 CASH AND CASH EQUIVALENTS, END OF YEAR $ 185.2 $ — $ 25.6 $ 234.6 $ — $ 445.4 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ (101.3 ) $ (46.5 ) $ (116.9 ) $ 1,342.1 $ — $ 1,077.4 INVESTING ACTIVITIES Purchases of short-term investments (2,047.1 ) (5.5 ) — (422.0 ) — (2,474.6 ) Additions to property and equipment — — — (322.2 ) — (322.2 ) Maturities of short-term investments 2,062.0 — — 150.0 — 2,212.0 Net proceeds from disposition of assets — — — 9.8 — 9.8 Purchase of affiliate debt (237.9 ) — — — 237.9 — Net cash used in investing activities of continuing operations (223.0 ) (5.5 ) — (584.4 ) 237.9 (575.0 ) FINANCING ACTIVITIES Proceeds from debt issuance — — — 849.5 — 849.5 Reduction of long-term borrowing (626.0 ) — — — (237.9 ) (863.9 ) Proceeds from equity issuance 585.5 — — — — 585.5 Cash dividends paid (11.6 ) — — — — (11.6 ) Debt issuance costs (23.4 ) — — — — (23.4 ) Advances from (to) affiliates 1,200.6 52.0 134.7 (1,387.3 ) — — Other (2.2 ) — — (4.9 ) — (7.1 ) Net cash provided by (used in) financing activities 1,122.9 52.0 134.7 (542.7 ) (237.9 ) 529.0 Net cash provided by discontinued operations — — — 8.4 — 8.4 Effect of exchange rate changes on cash and cash equivalents — — — (1.4 ) — (1.4 ) NET INCREASE IN CASH AND CASH EQUIVALENTS 798.6 — 17.8 222.0 — 1,038.4 CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 94.0 — 2.0 25.3 — 121.3 CASH AND CASH EQUIVALENTS, END OF YEAR $ 892.6 $ — $ 19.8 $ 247.3 $ — $ 1,159.7

Unaudited Quarterly Financial D

Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Unaudited Quarterly Financial Data	UNAUDITED QUARTERLY FINANCIAL DATA The following tables summarize our unaudited quarterly condensed consolidated income statement data for the years ended December 31, 2018 and 2017 (in millions, except per share amounts): 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Year Operating revenues $ 417.0 $ 458.5 $ 430.9 $ 399.0 $ 1,705.4 Operating expenses Contract drilling (exclusive of depreciation) 325.2 344.3 327.1 322.8 1,319.4 Loss on impairment (1) — — — 40.3 40.3 Depreciation 115.2 120.7 120.6 122.4 478.9 General and administrative 27.9 26.1 25.1 23.6 102.7 Operating loss (51.3 ) (32.6 ) (41.9 ) (110.1 ) (235.9 ) Other expense, net (70.7 ) (84.8 ) (77.7 ) (69.8 ) (303.0 ) Loss from continuing operations before income taxes (122.0 ) (117.4 ) (119.6 ) (179.9 ) (538.9 ) Income tax expense 18.4 24.7 23.3 23.2 89.6 Loss from continuing operations (140.4 ) (142.1 ) (142.9 ) (203.1 ) (628.5 ) Loss from discontinued operations, net (.1 ) (8.0 ) — — (8.1 ) Net loss (140.5 ) (150.1 ) (142.9 ) (203.1 ) (636.6 ) Net (income) loss attributable to noncontrolling interests .4 (.9 ) (2.1 ) (.5 ) (3.1 ) Net loss attributable to Ensco $ (140.1 ) $ (151.0 ) $ (145.0 ) $ (203.6 ) $ (639.7 ) Loss per share – basic and diluted Continuing operations $ (.32 ) $ (.33 ) $ (.33 ) $ (.47 ) $ (1.45 ) Discontinued operations — (.02 ) — — (.02 ) $ (.32 ) $ (.35 ) $ (.33 ) $ (.47 ) $ (1.47 ) (1) Fourth quarter included an aggregate loss of $40.3 million associated with the impairment of an older, non-core jackup rig. See "Note 5 - Property and Equipment" for additional information. 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Year Operating revenues $ 471.1 $ 457.5 $ 460.2 $ 454.2 $ 1,843.0 Operating expenses Contract drilling (exclusive of depreciation) (1) 278.1 291.3 285.8 334.3 1,189.5 Loss on impairment (2) — — — 182.9 182.9 Depreciation 109.2 107.9 108.2 119.5 444.8 General and administrative (3) 26.0 30.5 30.4 70.9 157.8 Operating income (loss) 57.8 27.8 35.8 (253.4 ) (132.0 ) Other income (expense), net (4) (57.7 ) (53.2 ) (40.4 ) 87.3 (64.0 ) Income (loss) from continuing operations before income taxes .1 (25.4 ) (4.6 ) (166.1 ) (196.0 ) Income tax expense (5) 24.1 19.3 23.4 42.4 109.2 Loss from continuing operations (24.0 ) (44.7 ) (28.0 ) (208.5 ) (305.2 ) Income (loss) from discontinued operations, net (.6 ) .4 (.2 ) 1.4 1.0 Net loss (24.6 ) (44.3 ) (28.2 ) (207.1 ) (304.2 ) Net (income) loss attributable to noncontrolling interests (1.1 ) (1.2 ) 2.8 — .5 Net loss attributable to Ensco $ (25.7 ) $ (45.5 ) $ (25.4 ) $ (207.1 ) $ (303.7 ) Loss per share – basic and diluted Continuing operations $ (.09 ) $ (.15 ) $ (.08 ) $ (.49 ) $ (.91 ) Discontinued operations — — — — — $ (.09 ) $ (.15 ) $ (.08 ) $ (.49 ) $ (.91 ) (1) Fourth quarter included $7.0 million of integration costs associated with the Atwood Merger. See "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations" in Part II for additional information. (2) Fourth quarter included an aggregate loss of $182.9 million associated with the impairment of certain rigs. See "Note 5 - Property and Equipment" for additional information. (3) Fourth quarter included integration costs of $30.9 million and merger-related costs consisting of various advisory, legal, accounting, valuation and other professional or consulting fees totaling $11.5 million . See "Note 3 - Acquisition of Atwood" for additional information. (4) Fourth quarter included a bargain purchase gain of $140.2 million related to the Atwood Merger. See "Note 3 - Acquisition of Atwood" for additional information. (5) Fourth quarter included net discrete tax expense of $16.5 million in connection with enactment of U.S. tax reform. See "Note 10 - Income taxes" for additional information.

Description Of The Business A_2

Description Of The Business And Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Business	Business We are one of the leading providers of offshore contract drilling services to the international oil and gas industry. We own and operate an offshore drilling rig fleet of 56 rigs spanning most of the strategic markets around the globe. We also have three rigs under construction. Inclusive of our rigs under construction, our fleet includes 12 drillships, 9 dynamically positioned semisubmersible rigs, three moored semisubmersible rigs and 35 jackup rigs. We operate the world's largest fleet amongst competitive rigs, including one of the newest ultra-deepwater fleets in the industry and a leading premium jackup fleet. Our customers include many of the leading national and international oil companies, in addition to many independent operators. We are among the most geographically diverse offshore drilling companies, with current operations spanning 14 countries on six continents. The markets in which we operate include the Gulf of Mexico, Brazil, the Mediterranean, the North Sea, the Middle East, West Africa, Australia and Southeast Asia. We provide drilling services on a day rate contract basis. Under day rate contracts, we provide an integrated service that includes the provision of a drilling rig and rig crews for which we receive a daily rate that may vary between the full rate and zero rate throughout the duration of the contractual term, depending on the operations of the rig. We also may receive lump-sum fees or similar compensation for the mobilization, demobilization and capital upgrades of our rigs. Our customers bear substantially all of the costs of constructing the well and supporting drilling operations, as well as the economic risk relative to the success of the well.
Merger	Merger On October 6, 2017 (the "Merger Date"), we completed a merger transaction (the "Atwood Merger") with Atwood Oceanics, Inc. ("Atwood") and Echo Merger Sub, LLC, a wholly-owned subsidiary of Ensco plc. Pursuant to the merger agreement, Echo Merger Sub, LLC, merged with and into Atwood, with Atwood as the surviving entity and an indirect, wholly-owned subsidiary of Ensco plc. Total consideration delivered in the Atwood Merger consisted of 132.2 million of our Class A ordinary shares and $11.1 million of cash in settlement of certain share-based payment awards. The total aggregate value of consideration transferred was $781.8 million . Additionally, upon closing of the Atwood Merger, we utilized cash acquired of $445.4 million and cash on hand to extinguish Atwood's revolving credit facility, outstanding senior notes and accrued interest totaling $1.3 billion . The estimated fair values assigned to assets acquired net of liabilities assumed exceeded the consideration transferred, resulting in a bargain purchase gain of $140.2 million that was recognized during the fourth quarter of 2017. During 2018, we recognized measurement period adjustments as we completed our fair value assessments resulting in additional bargain purchase gain of $1.8 million .
Basis Of Presentation-U.K. Companies Act 2006 Section 435 Statement	Basis of Presentation—U.K. Companies Act 2006 Section 435 Statement The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP, which the Board of Directors consider to be the most meaningful presentation of our results of operations and financial position. The accompanying consolidated financial statements do not constitute U.K. statutory accounts for the year ended December 31, 2018 and 2017 as required to be prepared under the U.K. Companies Act 2006. The U.K. statutory accounts are prepared in accordance with Financial Reporting Standard 102, the financial reporting standard applicable in the U.K. and Republic of Ireland (“FRS 102”). The auditor has reported on the U.K. statutory accounts for the year ended December 31, 2017; their report was (i) unqualified, (ii) did not include a reference to any matters to which the auditor drew attention by way of emphasis without qualifying their report and (iii) did not contain a statement under section 498 (2) or (3) of the U.K. Companies Act 2006. The U.K. statutory accounts for the year ended December 31, 2018 have yet to be finalized and will be delivered to the U.K. registrar of companies during 2019.
Principles Of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Ensco plc, those of our wholly-owned subsidiaries and entities in which we hold a controlling financial interest. All intercompany accounts and transactions have been eliminated. Certain previously reported amounts have been reclassified to conform to the current year presentation.
Pervasiveness Of Estimates	Pervasiveness of Estimates The preparation of financial statements in conformity with U.S. GAAP requires us to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the related revenues and expenses and disclosures of gain and loss contingencies as of the date of the financial statements. Actual results could differ from those estimates.
Foreign Currency Remeasurement And Translation	Foreign Currency Remeasurement and Translation Our functional currency is the U.S. dollar. As is customary in the oil and gas industry, a majority of our revenues and expenses are denominated in U.S. dollars; however, a portion of the revenues earned and expenses incurred by certain of our subsidiaries are denominated in currencies other than the U.S. dollar. These transactions are remeasured in U.S. dollars based on a combination of both current and historical exchange rates. Most transaction gains and losses, including certain gains and losses on our derivative instruments, are included in other, net, in our consolidated statement of operations. Certain gains and losses from the translation of foreign currency balances of our non-U.S. dollar functional currency subsidiaries are included in accumulated other comprehensive income on our consolidated balance sheet. Net foreign currency exchange losses, inclusive of offsetting fair value derivatives, were $17.2 million , $5.1 million and $6.0 million , and were included in other, net, in our consolidated statements of operations for the years ended December 31, 2018, 2017 and 2016 , respectively.
Cash Equivalents And Short-Term Investments	Cash Equivalents and Short-Term Investments Highly liquid investments with maturities of three months or less at the date of purchase are considered cash equivalents. Highly liquid investments with maturities of greater than three months but less than one year at the date of purchase are classified as short-term investments. Short-term investments consisted of time deposits with initial maturities in excess of three months but less than one year and totaled $329.0 million and $440.0 million as of December 31, 2018 and 2017 , respectively. Cash flows from purchases and maturities of short-term investments were classified as investing activities in our consolidated statements of cash flows for the years ended December 31, 2018, 2017 and 2016 . To mitigate our credit risk, our investments in time deposits are diversified across multiple, high-quality financial institutions.
Property And Equipment	Property and Equipment All costs incurred in connection with the acquisition, construction, major enhancement and improvement of assets are capitalized, including allocations of interest incurred during periods that our drilling rigs are under construction or undergoing major enhancements and improvements. Costs incurred to place an asset into service are capitalized, including costs related to the initial mobilization of a newbuild drilling rig. Repair and maintenance costs are charged to contract drilling expense in the period in which they are incurred. Upon the sale or retirement of assets, the related cost and accumulated depreciation are removed from the balance sheet, and the resulting gain or loss is included in contract drilling expense, unless reclassified to discontinued operations. Our property and equipment is depreciated on a straight-line basis, after allowing for salvage values, over the estimated useful lives of our assets. Drilling rigs and related equipment are depreciated over estimated useful lives ranging from four to 35 years. Buildings and improvements are depreciated over estimated useful lives ranging from seven to 30 years. Other equipment, including computer and communications hardware and software costs, is depreciated over estimated useful lives ranging from three to six years. We evaluate the carrying value of our property and equipment for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. For property and equipment used in our operations, recoverability generally is determined by comparing the carrying value of an asset to the expected undiscounted future cash flows of the asset. If the carrying value of an asset is not recoverable, the amount of impairment loss is measured as the difference between the carrying value of the asset and its estimated fair value. Property and equipment held-for-sale is recorded at the lower of net book value or fair value less cost to sell. We recorded pre-tax, non-cash impairment losses related to long-lived assets of $40.3 million and $182.9 million during 2018 and 2017, respectively. See "Note 5 - Property and Equipment" for additional information on our impairment charges. If the global economy deteriorates and/or our expectations relative to future offshore drilling industry conditions decline, it is reasonably possible that additional impairment charges may occur with respect to specific individual rigs, groups of rigs, such as a specific type of drilling rig, or rigs in a certain geographic location
Operating Revenues And Expenses	Operating Revenues and Expenses See "Note 2 - Revenue from Contracts with Customers" for information on our accounting policies for revenue recognition and certain operating costs that are deferred and amortized over future periods, which reflects our revenue recognition policies subsequent to our adoption of ASC Topic 606, Revenue from Contracts with Customers , effective January 1, 2018. Prior to our adoption of ASC Topic 606, we recognized revenue in accordance with prior guidance under ASC Topic 605. With the exception of a change in our policy to recognize demobilization revenue over the related contract term, if certain conditions are met, our revenue recognition policies are substantively unchanged as a result of our adoption of ASC Topic 606.
Derivative Instruments	Derivative Instruments We use derivatives to reduce our exposure to various market risks, primarily foreign currency exchange rate risk. See "Note 7 - Derivative Instruments" for additional information on how and why we use derivatives. All derivatives are recorded on our consolidated balance sheet at fair value. Derivatives subject to legally enforceable master netting agreements are not offset on our consolidated balance sheet. Accounting for the gains and losses resulting from changes in the fair value of derivatives depends on the use of the derivative and whether it qualifies for hedge accounting. Derivatives qualify for hedge accounting when they are formally designated as hedges and are effective in reducing the risk exposure that they are designated to hedge. Changes in the fair value of derivatives that are designated as hedges of the variability in expected future cash flows associated with existing recognized assets or liabilities or forecasted transactions ("cash flow hedges") are recorded in accumulated other comprehensive income ("AOCI"). Amounts recorded in AOCI associated with cash flow hedges are subsequently reclassified into contract drilling, depreciation or interest expense as earnings are affected by the underlying hedged forecasted transactions. Gains and losses on a cash flow hedge, or a portion of a cash flow hedge, that no longer qualifies as effective due to an unanticipated change in the forecasted transaction are recognized currently in earnings and included in other, net, in our consolidated statement of operations based on the change in the fair value of the derivative. When a forecasted transaction becomes probable of not occurring, gains and losses on the derivative previously recorded in AOCI are reclassified currently into earnings and included in other, net, in our consolidated statement of operations. We occasionally enter into derivatives that hedge the fair value of recognized assets or liabilities, but do not designate such derivatives as hedges or the derivatives otherwise do not qualify for hedge accounting. In these situations, a natural hedging relationship generally exists where changes in the fair value of the derivatives offset changes in the fair value of the underlying hedged items. Changes in the fair value of these derivatives are recognized currently in earnings in other, net, in our consolidated statement of operations. Derivatives with asset fair values are reported in other current assets or other assets, net, on our consolidated balance sheet depending on maturity date. Derivatives with liability fair values are reported in accrued liabilities and other, or other liabilities on our consolidated balance sheet depending on maturity date.
Income Taxes	Income Taxes We conduct operations and earn income in numerous countries. Current income taxes are recognized for the amount of taxes payable or refundable based on the laws and income tax rates in the taxing jurisdictions in which operations are conducted and income is earned. Deferred tax assets and liabilities are recognized for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the enacted tax rates in effect at year-end. A valuation allowance for deferred tax assets is recorded when it is more-likely-than-not that the benefit from the deferred tax asset will not be realized. We do not offset deferred tax assets and deferred tax liabilities attributable to different tax paying jurisdictions. We operate in certain jurisdictions where tax laws relating to the offshore drilling industry are not well developed and change frequently. Furthermore, we may enter into transactions with affiliates or employ other tax planning strategies that generally are subject to complex tax regulations. As a result of the foregoing, the tax liabilities and assets we recognize in our financial statements may differ from the tax positions taken, or expected to be taken, in our tax returns. Our tax positions are evaluated for recognition using a more-likely-than-not threshold, and those tax positions requiring recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon effective settlement with a taxing authority that has full knowledge of all relevant information. Interest and penalties relating to income taxes are included in current income tax expense in our consolidated statement of operations. Our drilling rigs frequently move from one taxing jurisdiction to another based on where they are contracted to perform drilling services. The movement of drilling rigs among taxing jurisdictions may involve a transfer of drilling rig ownership among our subsidiaries through an intercompany rig sale. The pre-tax profit resulting from an intercompany rig sale is eliminated from our consolidated financial statements, and the carrying value of a rig sold in an intercompany transaction remains at historical net depreciated cost prior to the transaction. Our consolidated financial statements do not reflect the asset disposition transaction of the selling subsidiary or the asset acquisition transaction of the acquiring subsidiary. Prior to our adoption of Accounting Standards Update 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“Update 2016-16”) on January 1, 2017, income taxes resulting from an intercompany rig sale, as well as the tax effect of any reversing temporary differences resulting from the sale, were deferred and amortized on a straight-line basis over the remaining useful life of the rig. Subsequent to our adoption of Update 2016-16, the income tax effects resulting from intercompany rig sales are recognized in earnings in the period in which the sale occurs. In some instances, we may determine that certain temporary differences will not result in a taxable or deductible amount in future years, as it is more-likely-than-not we will commence operations and depart from a given taxing jurisdiction without such temporary differences being recovered or settled. Under these circumstances, no future tax consequences are expected and no deferred taxes are recognized in connection with such operations. We evaluate these determinations on a periodic basis and, in the event our expectations relative to future tax consequences change, the applicable deferred taxes are recognized or derecognized. We do not provide deferred taxes on the undistributed earnings of certain subsidiaries because our policy and intention is to reinvest such earnings indefinitely. Should we make a distribution from these subsidiaries in the form of dividends or otherwise, we may be subject to additional income taxes. The U.S. Tax Cuts and Jobs Act (“U.S. tax reform”) was enacted on December 22, 2017 and introduced significant changes to U.S. income tax law, including a reduction in the statutory income tax rate from 35% to 21% effective January 1, 2018, a one-time transition tax on deemed repatriation of deferred foreign income, a base erosion anti-abuse tax that effectively imposes a minimum tax on certain payments to non-U.S. affiliates, new and revised rules relating to the current taxation of certain income of foreign subsidiaries and revised rules associated with limitations on the deduction of interest. See "Note 10 - Income Taxes" for additional information.
Share-Based Compensation	Share-Based Compensation We sponsor share-based compensation plans that provide equity compensation to our key employees, officers and non-employee directors. Our Long-Term Incentive Plan (the “2018 LTIP”) allows our Board of Directors to authorize share grants to be settled in cash or shares. Compensation expense for share awards to be settled in shares is measured at fair value on the date of grant and recognized on a straight-line basis over the requisite service period (usually the vesting period). Compensation expense for share awards to be settled in cash is remeasured each quarter with a cumulative adjustment to compensation cost during the period based on changes in our share price. Any adjustments to the compensation cost recognized in our consolidated statement of operations for awards that are forfeited are recognized in the period in which the forfeitures occur. See "Note 9 - Benefit Plans" for additional information on our share-based compensation.
Fair Value Measurements	Fair Value Measurements We measure certain of our assets and liabilities based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy assigns the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities ("Level 1") and the lowest priority to unobservable inputs ("Level 3"). Level 2 measurements represent inputs that are observable for similar assets or liabilities, either directly or indirectly, other than quoted prices included within Level 1. See "Note 4 - Fair Value Measurements" for additional information on the fair value measurement of certain of our assets and liabilities.
Noncontrolling Interests	Noncontrolling Interests Third parties hold a noncontrolling ownership interest in certain of our non-U.S. subsidiaries. Noncontrolling interests are classified as equity on our consolidated balance sheet and net income attributable to noncontrolling interests is presented separately in our consolidated statement of operations. For each of the years in the three-year period ended December 31, 2018 , all income attributable to noncontrolling interest was from continuing operations.
Earnings Per Share	Earnings Per Share We compute basic and diluted earnings per share ("EPS") in accordance with the two-class method. Net income (loss) attributable to Ensco used in our computations of basic and diluted EPS is adjusted to exclude net income allocated to non-vested shares granted to our employees and non-employee directors. Weighted-average shares outstanding used in our computation of diluted EPS is calculated using the treasury stock method and includes the effect of all potentially dilutive performance awards and excludes non-vested shares. In each of the years in the three-year period ended December 31, 2018 , our potentially dilutive instruments were not included in the computation of diluted EPS as the effect of including these shares in the calculation would have been anti-dilutive. The following table is a reconciliation of income (loss) from continuing operations attributable to Ensco shares used in our basic and diluted EPS computations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Income (loss) from continuing operations attributable to Ensco $ (631.6 ) $ (304.7 ) $ 882.1 Income from continuing operations allocated to non-vested share awards (.5 ) (.4 ) (16.6 ) Income (loss) from continuing operations attributable to Ensco shares $ (632.1 ) $ (305.1 ) $ 865.5 Anti-dilutive share awards totaling 1.5 million , 2.0 million and 500,000 for the years ended December 31, 2018, 2017 and 2016 , respectively, were excluded from the computation of diluted EPS. During 2016, we issued our 3.00% exchangeable senior notes due 2024 (the "2024 Convertible Notes"). See "Note 6 - Debt" for additional information on this issuance. We have the option to settle the notes in cash, shares or a combination thereof for the aggregate amount due upon conversion. Our intent is to settle the principal amount of the 2024 Convertible Notes in cash upon conversion. If the conversion value exceeds the principal amount (i.e., our share price exceeds the exchange price on the date of conversion), we expect to deliver shares equal to the remainder of our conversion obligation in excess of the principal amount. During each respective reporting period that our average share price exceeds the exchange price, an assumed number of shares required to settle the conversion obligation in excess of the principal amount will be included in our denominator for the computation of diluted EPS using the treasury stock method. Our average share price did not exceed the exchange price during the years ended December 31, 2018 and December 31, 2017 .
New Accounting Pronouncements	New Accounting Pronouncements Recently adopted accounting standards In August 2018, the Financial Accounting Standards Board (the "FASB") issued Update 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract ("Update 2018-15"), which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that included an internal-use software license). This update is effective for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years, with early adoption permitted. We elected to early-adopt Update 2018-15 effective October 1, 2018. As a result of adopting Update 2018-15, we began deferring and amortizing certain costs incurred to implement cloud computing arrangements that would have been recognized as incurred under previous guidance. We do not expect our adoption of Update 2018-15 to have a material impact on our financial position or results of operations in future periods. In February 2018, 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 U.S. tax reform. 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 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 consolidated balance sheet as of January 1, 2017. 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. Recently issued accounting standards 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. However, we do not expect our adoption of Update 2017-12 to have a material impact on our financial position or results of operations. 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 July 2018, the FASB issued Accounting Standard Update 2018-11, Leases (Topic 842), Targeted Improvements, 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, by class of underlying asset, to not separate lease and non-lease components and account for the combined component under Topic 606 when the non-lease component is the predominant element of the combined component. The lessor practical expedient is limited to circumstances in which the lease, if accounted for separately, would be classified as an operating lease under Topic 842. While we are still finalizing our analysis, we believe the non-lease component of our contracts is the predominant element and that the lease component, if accounted for separately, would be classified as an operating lease. Accordingly, we expect that substantially all of our contracts will qualify for the practical expedient provided for in Update 2018-11. Therefore, we expect to elect the practical expedient prescribed in Update 2018-11 and account for the combined component as a single component under Topic 606. We do not expect our adoption to 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. With respect to leases whereby we are the lessee, we expect to recognize upon adoption on January 1, 2019 lease liabilities ranging from approximately $75 million to $80 million and offsetting "right of use" assets ranging from approximately $65 million to $70 million . Our adoption of Update 2016-02 is not expected to have a material impact on our ability to comply with current debt covenants. With the exception of the updated standards discussed above, there have been no accounting pronouncements issued and not yet effective that have significance, or potential significance, to our consolidated financial statements.

Description Of The Business A_3

Description Of The Business And Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Reconciliation Of Net Income Attributable To Ensco Shares Used In Basic And Diluted EPS Computations	The following table is a reconciliation of income (loss) from continuing operations attributable to Ensco shares used in our basic and diluted EPS computations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Income (loss) from continuing operations attributable to Ensco $ (631.6 ) $ (304.7 ) $ 882.1 Income from continuing operations allocated to non-vested share awards (.5 ) (.4 ) (16.6 ) Income (loss) from continuing operations attributable to Ensco shares $ (632.1 ) $ (305.1 ) $ 865.5

Revenue from Contracts with Cus

Revenue from Contracts with Customers (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset and Liability [Table Text Block]	The following table summarizes our contract assets and contract liabilities (in millions): December 31, 2018 December 31, 2017 Current contract assets $ 4.0 $ 3.0 Noncurrent contract assets $ — $ 2.8 Current contract liabilities (deferred revenue) $ 56.9 $ 71.9 Noncurrent contract liabilities (deferred revenue) $ 20.5 $ 51.2 Changes in contract assets and liabilities during the period are as follows (in millions): Contract Assets Contract Liabilities Balance as of December 31, 2017 $ 5.8 $ 123.1 Revenue recognized in advance of right to bill customer 2.2 — Increase due to cash received — 49.4 Decrease due to amortization of deferred revenue that was included in the beginning contract liability balance — (72.0 ) Decrease due to amortization of deferred revenue that was added during the period — (23.1 ) Decrease due to transfer to receivables during the period (4.0 ) — Balance as of December 31, 2018 $ 4.0 $ 77.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	Expected future amortization of our contract liabilities and deferred costs recorded as of December 31, 2018 is set forth in the table below (in millions): 2019 2020 2021 2022 and Thereafter Total Amortization of contract liabilities $ 57.0 $ 11.7 $ 7.2 $ 1.5 $ 77.4 Amortization of deferred costs $ 23.8 $ 9.4 $ 2.4 $ 1.5 $ 37.1

Acquisition Of Atwood (Tables)

Acquisition Of Atwood (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Provisional Amounts for Assets Acquired and Liabilities Assumed	The provisional amounts recorded for assets acquired and liabilities assumed as of the Merger Date and respective measurement period adjustments were as follows (in millions): Amounts Recognized as of Merger Date Measurement Period Adjustments (1) Estimated Fair Value Assets: Cash and cash equivalents (2) $ 445.4 $ — $ 445.4 Accounts receivable (3) 62.3 (1.6 ) 60.7 Other current assets 118.1 4.6 122.7 Property and equipment 1,762.0 9.2 1,771.2 Other assets 23.7 (5.1 ) 18.6 Liabilities: Accounts payable and accrued liabilities 64.9 (1.1 ) 63.8 Other liabilities 118.7 6.4 125.1 Net assets acquired 2,227.9 1.8 2,229.7 Less: Merger consideration (781.8 ) (781.8 ) Repayment of Atwood debt (2) (1,305.9 ) (1,305.9 ) Bargain purchase gain $ 140.2 $ 142.0 (1) The measurement period adjustments reflect changes in the estimated fair values of certain assets and liabilities, primarily related to inventory, capital equipment and other liabilities. The measurement period adjustments were recorded to reflect new information obtained about facts and circumstances existing as of the Merger Date and did not result from subsequent intervening events. (2) Upon closing of the Atwood Merger, we utilized acquired cash of $445.4 million and cash on hand from the liquidation of short-term investments to repay Atwood's debt and accrued interest of $1.3 billion . (3) Gross contractual amounts receivable totaled $64.7 million as of the Merger Date.
Business Acquisition, Pro Forma Information	The pro forma results do not include any potential synergies or non-recurring charges resulting directly from the Atwood Merger. (in millions, except per share amounts) Twelve Months Ended (Unaudited) 2017 (1) 2016 Revenues $ 2,226.0 $ 3,622.1 Net income (loss) (347.0 ) 1,284.9 Earnings (loss) per share - basic and diluted (.80 ) 3.18 (1) Pro forma net income and earnings per share were adjusted to exclude an aggregate $80.7 million of merger-related and integration costs incurred by Ensco and Atwood during 2017 and the $140.2 million estimated bargain purchase gain.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Schedule Of Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following fair value hierarchy table categorizes information regarding our net financial assets measured at fair value on a recurring basis as of December 31, 2018 and 2017 (in millions): Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total As of December 31, 2018 Supplemental executive retirement plan assets $ 27.2 $ — $ — $ 27.2 Total financial assets 27.2 — — 27.2 Derivatives, net — (10.7 ) — (10.7 ) Total financial liabilities $ — $ (10.7 ) $ — $ (10.7 ) As of December 31, 2017 Supplemental executive retirement plan assets $ 30.9 $ — $ — $ 30.9 Derivatives, net — 6.8 — 6.8 Total financial assets $ 30.9 $ 6.8 $ — $ 37.7
Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments	The carrying values and estimated fair values of our debt instruments as of December 31, 2018 and 2017 were as follows (in millions): December 31, 2018 December 31, 2017 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value 8.50% Senior notes due 2019 (1) $ — $ — $ 251.4 $ 252.9 6.875% Senior notes due 2020 (1) 127.5 121.6 477.9 473.1 4.70% Senior notes due 2021 (1) 112.7 101.8 267.1 265.3 3.00% Exchangeable senior notes due 2024 (2) 666.8 575.5 635.7 757.1 4.50% Senior notes due 2024 619.8 405.2 619.3 527.1 8.00% Senior notes due 2024 337.0 273.7 337.9 333.8 5.20% Senior notes due 2025 664.4 443.9 663.6 571.4 7.75% Senior notes due 2026 985.0 725.5 — — 7.20% Debentures due 2027 149.3 109.1 149.3 141.9 7.875% Senior notes due 2040 375.0 223.2 376.7 258.8 5.75% Senior notes due 2044 972.9 566.3 971.8 690.4 Total $ 5,010.4 $ 3,545.8 $ 4,750.7 $ 4,271.8 (1) The decline in the carrying value of our 8.50% senior notes due 2019, 6.875% senior notes due 2020 and our 4.70% senior notes due 2021 from December 31, 2017 to December 31, 2018 is primarily due to debt repurchases and redemptions as discussed in "Note 6 - Debt". (2) Our 3.00% exchangeable senior notes due 2024 (the "2024 Convertible Notes") were issued with a conversion feature. The 2024 Convertible Notes were separated into their liability and equity components on our consolidated balance sheet. The equity component was initially recorded to additional paid-in capital and as a debt discount, which will be amortized to interest expense. Excluding the unamortized discount, the carrying value of the 2024 Convertible Notes was $836.3 million and $834.0 million as of December 31, 2018 and 2017 . See "Note 6 - Debt" for additional information on this issuance.

Property And Equipment (Tables)

Property And Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule Of Property And Equipment	Property and equipment as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Drilling rigs and equipment $ 14,542.5 $ 12,272.4 Work-in-progress 779.2 2,876.3 Other 195.3 183.4 $ 15,517.0 $ 15,332.1

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt Instruments	The carrying value of our long-term debt as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 8.50% Senior notes due 2019 (1) $ — $ 251.4 6.875% Senior notes due 2020 (1) 127.5 477.9 4.70% Senior notes due 2021 (1) 112.7 267.1 3.00% Exchangeable senior notes due 2024 (2) 666.8 635.7 4.50% Senior notes due 2024 619.8 619.3 8.00% Senior notes due 2024 337.0 337.9 5.20% Senior notes due 2025 664.4 663.6 7.75% Senior notes due 2026 985.0 — 7.20% Debentures due 2027 149.3 149.3 7.875% Senior notes due 2040 375.0 376.7 5.75% Senior notes due 2044 972.9 971.8 Total long-term debt $ 5,010.4 $ 4,750.7 (1) The decline in the carrying value of our 8.50% senior notes due 2019, 6.875% senior notes due 2020 and our 4.70% senior notes due 2021 resulted from repurchases and redemptions during the first quarter of 2018 discussed below. (2) Our 2024 Convertible Notes were issued with a conversion feature. The 2024 Convertible Notes were separated into their liability and equity components on our consolidated balance sheet. The equity component was initially recorded to additional paid-in capital and as a debt discount that will be amortized to interest expense over the life of the instrument. Excluding the unamortized discount, the carrying value of the 2024 Convertible Notes was $836.3 million and $834.0 million as of December 31, 2018 and 2017 , respectively.
Convertible Debt	As of December 31, 2018 and 2017 , the 2024 Convertible Notes consist of the following (in millions): Liability component: 2018 2017 Principal $ 849.5 $ 849.5 Less: Unamortized debt discount and issuance costs (182.7 ) (213.8 ) Net carrying amount 666.8 635.7 Equity component, net $ 220.0 $ 220.0
Schedule of Extinguishment of Debt	Our tender offers and open market repurchases during the two-year period ended December 31, 2018 were as follows (in millions): Year Ended December 31, 2018 Aggregate Principal Amount Repurchased Aggregate Repurchase Price (1) 8.50% Senior notes due 2019 $ 237.6 $ 256.8 6.875% Senior notes due 2020 328.0 354.7 4.70% Senior notes due 2021 156.2 159.7 Total $ 721.8 $ 771.2 Year Ended December 31, 2017 Aggregate Principal Amount Repurchased Aggregate Repurchase Price (1) 8.50% Senior notes due 2019 $ 54.6 $ 60.1 6.875% Senior notes due 2020 100.1 105.1 4.70% Senior notes due 2021 39.4 39.3 Total $ 194.1 $ 204.5 (1) Excludes accrued interest paid to holders of the repurchased senior notes. During 2017, we completed exchange offers to exchange our outstanding 2019 Notes, 2020 Notes and 2021 Notes for our 8% 2024 Notes and cash. The exchange offers resulted in the tender of $649.5 million aggregate principal amount of our outstanding notes that were settled and exchanged as follows (in millions): Aggregate Principal Amount Repurchased 8% Senior Notes Due 2024 Consideration Cash Total Consideration 8.50% Senior notes due 2019 $ 145.8 $ 81.6 $ 81.7 $ 163.3 6.875% Senior notes due 2020 129.8 69.3 69.4 138.7 4.70% Senior notes due 2021 373.9 181.1 181.4 362.5 Total $ 649.5 $ 332.0 $ 332.5 $ 664.5
Aggregate Maturities Of Long-Term Debt	The descriptions of our senior notes above reflect the original principal amounts issued, which have subsequently changed as a result of our tenders, repurchases, exchanges, redemptions and new debt issuances such that the maturities of our debt were as follows (in millions): Senior Notes Original Principal 2016 Tenders, Repurchases and Equity Exchange 2017 Exchange Offers and Repurchases 2018 Tender Offers, Redemption and Debt Issuance Remaining Principal 8.50% due 2019 $ 500.0 $ (62.0 ) $ (200.4 ) $ (237.6 ) $ — 6.875% due 2020 900.0 (219.2 ) (229.9 ) (328.0 ) 122.9 4.70% due 2021 1,500.0 (817.0 ) (413.3 ) (156.2 ) 113.5 3.00% Exchangeable senior notes due 2024 849.5 — — — 849.5 4.50% due 2024 625.0 (1.7 ) — — 623.3 8.00% due 2024 — — 332.0 — 332.0 5.20% due 2025 700.0 (30.7 ) — — 669.3 7.75% due 2026 — — — 1,000.0 1,000.0 7.20% due 2027 150.0 — — — 150.0 7.875% due 2040 300.0 — — — 300.0 5.75% due 2044 1,025.0 (24.5 ) — — 1,000.5 Total $ 6,549.5 $ (1,155.1 ) $ (511.6 ) $ 278.2 $ 5,161.0

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivatives At Fair Value	Derivatives recorded at fair value on our consolidated balance sheets as of December 31, 2018 and 2017 consisted of the following (in millions): Derivative Assets Derivative Liabilities 2018 2017 2018 2017 Derivatives Designated as Hedging Instruments Foreign currency forward contracts - current (1) $ .2 $ 5.9 $ 8.3 $ .2 Foreign currency forward contracts - non-current (2) — .5 .4 .1 .2 6.4 8.7 .3 Derivatives not Designated as Hedging Instruments Foreign currency forward contracts - current (1) .4 .9 2.6 .2 Total $ .6 $ 7.3 $ 11.3 $ .5 (1) Derivative assets and liabilities that have maturity dates equal to or less than 12 months from the respective balance sheet dates were included in other current assets and accrued liabilities and other, respectively, on our consolidated balance sheets. (2) Derivative assets and liabilities that have maturity dates greater than 12 months from the respective balance sheet dates were included in other assets and other liabilities, respectively, on our consolidated balance sheets.
Gains And Losses On Derivatives Designated As Cash Flow Hedges	Gains and losses, net of tax, on derivatives designated as cash flow hedges included in our consolidated statements of operations and comprehensive income for each of the years in the three-year period ended December 31, 2018 were as follows (in millions): Gain (Loss) Recognized in Other Comprehensive Income ("OCI") on Derivatives (Effective Portion) (Gain) Loss Reclassified from AOCI into Income (Effective Portion) (1) Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing) (2) 2018 2017 2016 2018 2017 2016 2018 2017 2016 Interest rate lock contracts (3) $ — $ — $ — $ .2 $ .2 $ .2 $ — $ — $ — Foreign currency forward contracts (4) (9.7 ) 8.5 (5.4 ) (1.2 ) .2 12.2 (1.9 ) (.7 ) 1.9 Total $ (9.7 ) $ 8.5 $ (5.4 ) $ (1.0 ) $ .4 $ 12.4 $ (1.9 ) $ (.7 ) $ 1.9 (1) Changes in the fair value of cash flow hedges are recorded in AOCI. Amounts recorded in AOCI associated with cash flow hedges are subsequently reclassified into contract drilling, depreciation or interest expense as earnings are affected by the underlying hedged forecasted transaction. (2) Gains and losses recognized in income for amounts excluded from effectiveness testing were included in other, net, in our consolidated statements of operations. (3) Losses on interest rate lock derivatives reclassified from AOCI into income were included in interest expense, net, in our consolidated statements of operations. (4) During the year ended December 31, 2018 , $400,000 of gains were reclassified from AOCI into contract drilling expense and $800,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2017 , $1.1 million of losses were reclassified from AOCI into contract drilling expense and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2016 , $13.1 million of losses were reclassified from AOCI into contract drilling and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations.
Schedule Of Estimated Amount Of Net Gains Associated With Derivatives	As of December 31, 2018 , the estimated amount of net losses associated with derivatives, net of tax, that will be reclassified to earnings during the next 12 months was as follows (in millions): Net unrealized losses to be reclassified to contract drilling expense $ (5.2 ) Net realized gains to be reclassified to depreciation expense .8 Net realized losses to be reclassified to interest expense (.2 ) Net losses to be reclassified to earnings $ (4.6 )

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Schedule Of Activity In Our Various Shareholders' Equity	Activity in our various shareholders' equity accounts for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): Shares Par Value Additional Paid-in Capital Retained Earnings AOCI Treasury Shares Non-controlling Interest BALANCE, December 31, 2015 242.9 $ 24.4 $ 5,554.5 $ 985.3 $ 12.5 $ (63.8 ) $ 4.3 Net income — — — 890.2 — — 6.9 Dividends paid ($0.04 per share) — — — (11.4 ) — — — Distributions to noncontrolling interests — — — — — — (7.8 ) Equity issuance 65.6 6.5 579.0 — — — — Equity for debt exchange 1.8 .2 14.8 — — — — Equity component of convertible debt — — 220.0 — — — — Contributions from noncontrolling interests — — — — — — 1.0 Tax expense on share-based compensation — — (3.4 ) — — — — Repurchase of shares — — — — — (2.0 ) — Share-based compensation cost — — 37.3 — — — — Net other comprehensive loss — — — — 6.5 — — BALANCE, December 31, 2016 310.3 31.1 6,402.2 1,864.1 19.0 (65.8 ) 4.4 Net loss — — — (303.7 ) — — (.5 ) Dividends paid ($0.04 per share) — — — (13.6 ) — — — Cumulative-effect reduction from adoption of ASU 2016-16 — — — (14.1 ) — — — Distributions to noncontrolling interests — — — — — — (6.0 ) Equity issuance in connection with Atwood Merger 132.2 13.2 757.5 — — — — Shares issued under share-based compensation plans, net 4.5 .5 (.4 ) — — (1.3 ) — Repurchase of shares — — — — — (1.9 ) — Share-based compensation cost — — 35.7 — — — — Net other comprehensive income — — — — 9.6 — — BALANCE, December 31, 2017 447.0 44.8 7,195.0 1,532.7 28.6 (69.0 ) (2.1 ) Net loss — — — (639.7 ) — — 3.1 Dividends paid ($0.04 per share) — — — (18.0 ) — — — Cumulative-effect reduction from adoption of ASU 2018-02 — — — (.8 ) .8 — — Shares issued under share-based compensation plans, net 13.7 1.4 (.6 ) — — (1.3 ) — Distributions to noncontrolling interests — — — — — — (3.6 ) Repurchase of shares — — — — — (1.9 ) — Share-based compensation cost — — 30.6 — — — — Net other comprehensive income — — — — (11.2 ) — — BALANCE, December 31, 2018 460.7 $ 46.2 $ 7,225.0 $ 874.2 $ 18.2 $ (72.2 ) $ (2.6 )

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary Of Non-Vested Share Award Related Compensation Expense Recognized	The following table summarizes share award and cash-settled award compensation expense recognized during each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Contract drilling $ 18.9 $ 18.3 $ 19.9 General and administrative 14.5 14.5 16.6 33.4 32.8 36.5 Tax benefit (2.8 ) (4.8 ) (5.9 ) Total $ 30.6 $ 28.0 $ 30.6
Summary Of Value Of Non-Vested Share Awards Granted And Vested	The following table summarizes the value of share awards and cash-settled awards granted and vested during each of the years in the three-year period ended December 31, 2018 : Share Awards Cash-Settled Awards 2018 2017 2016 2018 2017 2016 Weighted-average grant-date fair value of share awards granted (per share) $ 6.16 $ 7.90 $ 10.42 $ 5.31 $ 6.27 $ 9.64 Total fair value of share awards vested during the period (in millions) $ 7.5 $ 8.6 $ 8.8 $ 9.9 $ 3.9 $ —
Summary Of Non-Vested Share Award Activity	The following table summarizes share awards and cash-settled awards activity for the year ended December 31, 2018 (shares in thousands): Share Awards Cash-settled Awards Awards Weighted-Average Grant-Date Fair Value Awards Weighted-Average Grant-Date Fair Value Share awards and cash-settled awards as of December 31, 2017 3,305 $ 16.06 7,089 $ 7.37 Granted 6,298 6.16 114 5.31 Vested (1,312 ) 19.85 (1,512 ) 7.53 Forfeited (225 ) 11.62 (574 ) 7.18 Share awards and cash-settled awards as of December 31, 2018 8,066 $ 7.84 5,117 $ 7.30

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Summary Of Components Of Provision For Income Taxes From Continuing Operations	The following table summarizes components of our provision for income taxes from continuing operations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Current income tax (benefit) expense: U.S. $ (19.9 ) $ (2.2 ) $ (6.6 ) Non-U.S. 52.9 56.4 86.4 33.0 54.2 79.8 Deferred income tax expense: U.S. 52.9 36.0 15.9 Non-U.S. 3.7 19.0 12.8 56.6 55.0 28.7 Total income tax expense $ 89.6 $ 109.2 $ 108.5
Summary Of Significant Components Of Deferred Income Tax Assets (Liabilities)	The following table summarizes significant components of deferred income tax assets and liabilities as of December 31, 2018 and 2017 (in millions): 2018 2017 Deferred tax assets : Net operating loss carryforwards $ 148.4 $ 187.1 Foreign tax credits 123.6 132.3 Interest limitation carryforwards 40.2 — Premiums on long-term debt 23.8 36.1 Employee benefits, including share-based compensation 15.4 20.7 Deferred revenue 10.3 26.0 Other 14.5 12.8 Total deferred tax assets 376.2 415.0 Valuation allowance (316.0 ) (278.8 ) Net deferred tax assets 60.2 136.2 Deferred tax liabilities : Property and equipment (54.5 ) (51.5 ) Deferred U.S. tax on foreign income (31.5 ) (24.8 ) Deferred costs (5.3 ) (9.1 ) Deferred transition tax — (13.7 ) Other (3.7 ) (8.7 ) Total deferred tax liabilities (95.0 ) (107.8 ) Net deferred tax asset (liability) $ (34.8 ) $ 28.4
Summary Of Effective Income Tax Rate On Continuing Operations	Our consolidated effective income tax rate on continuing operations for each of the years in the three-year period ended December 31, 2018 , differs from the U.K. statutory income tax rate as follows: 2018 2017 2016 U.K. statutory income tax rate 19.0 % 19.2 % 20.0 % Non-U.K. taxes (18.0 ) (40.4 ) (7.9 ) Valuation allowance (16.9 ) (18.0 ) 2.6 Debt repurchases (1.6 ) (2.8 ) (4.1 ) Asset impairments (1.4 ) (17.1 ) — Bargain purchase gain (.2 ) 13.8 — U.S. tax reform 2.2 (8.4 ) — Tax restructuring transaction 1.7 — — Other (1.4 ) (2.0 ) .3 Effective income tax rate (16.6 )% (55.7 )% 10.9 %
Summary Of Reconciliation Of The Beginning And Ending Amount Of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended December 31, 2018 and 2017 is as follows (in millions): 2018 2017 Balance, beginning of year $ 147.6 $ 122.0 Increases in unrecognized tax benefits as a result of tax positions taken during the current year 6.5 5.4 Impact of foreign currency exchange rates (5.0 ) 8.1 Lapse of applicable statutes of limitations (4.5 ) (.4 ) Increase in unrecognized tax benefits as a result of tax positions taken during prior years 2.5 .7 Decreases in unrecognized tax benefits as a result (3.8 ) (.2 ) Settlements with taxing authorities (.3 ) (10.2 ) Increases in unrecognized tax benefits as a result of the Atwood Merger — 22.2 Balance, end of year $ 143.0 $ 147.6

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Summary Of Rig Sales and Income From Discontinued Operations	The following rig sales were included in discontinued operations during the three-year period ended December 31, 2018 (in millions): Rig Date of Sale Segment (1) Net Proceeds Net Book Value (2) Pre-tax Gain (Loss) ENSCO 7500 April 2018 Floaters $ 2.6 $ 1.5 $ 1.1 ENSCO 90 June 2017 Jackups .3 .3 — ENSCO DS-2 May 2016 Floaters 5.0 4.0 1.0 ENSCO 58 April 2016 Jackups .7 .3 .4 ENSCO 6000 April 2016 Floaters .6 .8 (.2 ) $ 9.2 $ 6.9 $ 2.3 (1) The rigs' operating results were reclassified to discontinued operations in our consolidated statements of operations for each of the years in the three-year period ended December 31, 2018 and were previously included within the specified operating segment. (2) Includes the rig's net book value as well as inventory and other assets on the date of the sale. The following table summarizes income (loss) from discontinued operations for each of the years in the three-year period ended December 31, 2018 (in millions): 2018 2017 2016 Revenues $ — $ — $ — Operating expenses 2.0 1.5 3.1 Operating loss (2.0 ) (1.5 ) (3.1 ) Income tax expense (benefit) 7.1 (2.1 ) (10.1 ) Gain on disposal of discontinued operations, net 1.0 .4 1.1 Income (loss) from discontinued operations $ (8.1 ) $ 1.0 $ 8.1

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Capital Commitments	The following table summarizes the cumulative amount of contractual payments made as of December 31, 2018 for our rigs under construction and estimated timing of our remaining contractual payments (in millions): Cumulative Paid (1) 2019 2020 Thereafter Total (2) ENSCO 123 (3) $ 276.4 $ 9.0 $ — $ — $ 285.4 ENSCO DS-14 (4) 15.0 — 165.0 — 180.0 ENSCO DS-13 (4) — 83.9 — — 83.9 $ 291.4 $ 92.9 $ 165.0 $ — $ 549.3 (1) Cumulative paid represents the aggregate amount of contractual payments made from commencement of the construction agreement through December 31, 2018 . Contractual payments made by Atwood prior to the Atwood Merger for ENSCO DS-13 and ENSCO DS-14 are excluded. (2) Total commitments are based on fixed-price shipyard construction contracts, exclusive of our internal costs associated with project management, commissioning and systems integration testing. Total commitments also exclude holding costs and interest. (3) In January 2018, we made a milestone payment of $207.4 million . The remaining unpaid balance of $9.0 million is due upon delivery. The $207.4 million milestone payment was invoiced and included in accounts payable - trade as of December 31, 2017 on our consolidated balance sheet. (4) The remaining milestone payments for ENSCO DS-13 and ENSCO DS-14 bear interest at a rate of 4.5% per annum, which accrues during the holding period until delivery. Delivery is scheduled for September 2019 and June 2020 for ENSCO DS-13 and ENSCO DS-14, respectively. Upon delivery, the remaining milestone payments and accrued interest thereon may be financed through a promissory note with the shipyard for each rig. The promissory notes will bear interest at a rate of 5.0% per annum with a maturity date of December 30, 2022 and will be secured by a mortgage on each respective rig. The remaining milestone payments for ENSCO DS-13 and ENSCO DS-14 are included in the table above in the period in which we expect to take delivery of the rig. However, we may elect to execute the promissory notes and defer payment until December 2022.

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting Information, Revenue for Reportable Segment [Abstract]
Schedule Of Segment Reporting Information	Year Ended December 31, 2018 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,013.5 $ 630.9 $ 61.0 $ 1,705.4 $ — $ 1,705.4 Operating expenses Contract drilling (exclusive of depreciation) 737.4 526.5 55.5 1,319.4 — 1,319.4 Loss on impairment — 40.3 — 40.3 — 40.3 Depreciation 311.8 153.3 — 465.1 13.8 478.9 General and administrative — — — — 102.7 102.7 Operating income (loss) $ (35.7 ) $ (89.2 ) $ 5.5 $ (119.4 ) $ (116.5 ) $ (235.9 ) Property and equipment, net $ 9,465.6 $ 3,114.1 $ — $ 12,579.7 $ 36.5 $ 12,616.2 Capital expenditures $ 105.5 $ 317.7 $ — $ 423.2 $ 3.5 $ 426.7 Year Ended December 31, 2017 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,143.5 $ 640.3 $ 59.2 $ 1,843.0 $ — $ 1,843.0 Operating expenses Contract drilling (exclusive of depreciation) 624.2 512.1 53.2 1,189.5 — 1,189.5 Loss on impairment 174.7 8.2 — 182.9 — 182.9 Depreciation 297.4 131.5 — 428.9 15.9 444.8 General and administrative — — — — 157.8 157.8 Operating income (loss) $ 47.2 $ (11.5 ) $ 6.0 $ 41.7 $ (173.7 ) $ (132.0 ) Property and equipment, net $ 9,650.9 $ 3,177.6 $ — $ 12,828.5 $ 45.2 $ 12,873.7 Capital expenditures $ 470.3 $ 62.1 $ — $ 532.4 $ 4.3 $ 536.7 Year Ended December 31, 2016 Floaters Jackups Other Operating Segments Total Reconciling Items Consolidated Total Revenues $ 1,771.1 $ 929.5 $ 75.8 $ 2,776.4 $ — $ 2,776.4 Operating expenses Contract drilling (exclusive of depreciation) 725.0 516.8 59.2 1,301.0 — 1,301.0 Depreciation 304.1 123.7 — 427.8 17.5 445.3 General and administrative — — — — 100.8 100.8 Operating income $ 742.0 $ 289.0 $ 16.6 $ 1,047.6 $ (118.3 ) $ 929.3 Property and equipment, net $ 8,300.4 $ 2,561.0 $ — $ 10,861.4 $ 57.9 $ 10,919.3 Capital expenditures $ 110.3 $ 206.2 $ — $ 316.5 $ 5.7 $ 322.2
Schedule Of Geographic Distribution Of Rigs By Segment	As of December 31, 2018 , the geographic distribution of our drilling rigs by operating segment was as follows: Floaters Jackups Total North & South America 8 4 12 Europe & the Mediterranean 7 11 18 Middle East & Africa 3 12 15 Asia & Pacific Rim 4 7 11 Asia & Pacific Rim (under construction) 2 1 3 Total 24 35 59
Schedule Of Revenues And Long-Lived Assets By Geographical Segment	Information by country for those countries that account for more than 10% of our long-lived assets as well as the United Kingdom, our country of domicile, was as follows (in millions): Long-lived Assets 2018 2017 2016 Spain $ 2,306.6 $ 2,004.2 $ 2,334.5 United States 2,270.0 2,764.9 2,898.3 Nigeria 1,368.2 583.3 — United Kingdom 1,185.2 609.4 409.0 Singapore 23.9 2,859.3 1,388.4 Other countries 5,462.3 4,052.6 3,889.1 Total $ 12,616.2 $ 12,873.7 $ 10,919.3

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Financial Information [Abstract]
Accounts Receivable, Net	Accounts receivable, net, as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Trade (1) $ 301.7 $ 335.4 Other 46.4 33.6 348.1 369.0 Allowance for doubtful accounts (1) (3.4 ) (23.6 ) $ 344.7 $ 345.4 (1) The decline in trade receivables and allowance for doubtful accounts is primarily due to the settlement with Petrobras described in "Note 12 - Commitments and Contingencies".
Other Current Assets	Other current assets as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Inventory $ 268.1 $ 278.8 Prepaid taxes 35.0 43.5 Deferred costs 23.5 29.7 Prepaid expenses 15.2 14.2 Other 19.1 15.0 $ 360.9 $ 381.2
Other Assets, Net	Other assets as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Deferred tax assets $ 29.4 $ 38.8 Supplemental executive retirement plan assets 27.2 30.9 Deferred costs 21.5 37.4 Intangible assets 2.5 15.7 Other 17.2 17.4 $ 97.8 $ 140.2
Accrued Liabilities And Other	Accrued liabilities and other as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Accrued interest $ 100.6 $ 83.1 Personnel costs 82.5 112.0 Deferred revenue 56.9 71.9 Income and other taxes payable 36.9 46.4 Derivative liabilities 10.9 .4 Other 30.2 12.1 $ 318.0 $ 325.9
Other Liabilities	Other liabilities as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Unrecognized tax benefits (inclusive of interest and penalties) $ 177.0 $ 178.0 Deferred tax liabilities 70.7 18.5 Intangible liabilities 53.5 59.6 Supplemental executive retirement plan liabilities 28.1 32.0 Personnel costs 25.1 18.1 Deferred revenue 20.5 51.2 Deferred rent 11.7 17.1 Other 9.4 12.2 $ 396.0 $ 386.7
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Accumulated other comprehensive income as of December 31, 2018 and 2017 consisted of the following (in millions): 2018 2017 Derivative instruments $ 12.6 $ 22.5 Currency translation adjustment 7.3 7.8 Other (1.7 ) (1.7 ) $ 18.2 $ 28.6
Repair And Maintenance Expense Related To Continuing Operations	Repair and maintenance expense related to continuing operations for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 Repair and maintenance expense $ 198.4 $ 188.7 $ 151.1
Schedule of Cash Flows Information	Net cash provided by (used in) operating activities of continuing operations attributable to the net change in operating assets and liabilities for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 (Increase) decrease in accounts receivable $ (6.2 ) $ 83.2 $ 222.4 (Increase) decrease in other assets (2.8 ) (14.0 ) 44.0 Decrease in liabilities (9.0 ) (3.8 ) (125.8 ) $ (18.0 ) $ 65.4 $ 140.6
Cash Paid For Interest And Income Taxes	Cash paid for interest and income taxes for each of the years in the three-year period ended December 31, 2018 was as follows (in millions): 2018 2017 2016 Interest, net of amounts capitalized $ 232.6 $ 199.8 $ 264.8 Income taxes 58.4 62.8 56.4
Revenue from External Customers by Products and Services [Table Text Block]	Consolidated revenues by customer for the years ended December 31, 2018 , 2017 and 2016 were as follows: 2018 2017 2016 Total (1) 15 % 22 % 13 % Saudi Aramco (2) 11 % 9 % 6 % Petrobras (1) 8 % 11 % 9 % BP (3) 7 % 15 % 12 % Other 59 % 43 % 60 % 100 % 100 % 100 % (1) For the years ended December 31, 2018, 2017 and 2016 , all Total and Petrobras revenues were attributable to the Floater segment. (2) For the years ended December 31, 2018, 2017 and 2016 , all Saudi Aramco revenues were attributable to the Jackup segment. (3) For the year ended December 31, 2018, 27% , 53% and 20% of BP revenues were attributable to our Floater, Other and Jackup segments, respectively. For the year ended December 31, 2017, 78% of BP revenues were attributable to our Floater segment and the remaining revenues were attributable to our Other segment. For the year ended December 31, 2016, 76% , 17% and 7% of BP revenues were attributable to our Floater, Other and Jackup segments, respectively.
Reconciliation of Revenue from Segments to Consolidated [Table Text Block]	Consolidated revenues by region, including the United Kingdom, our country of domicile, for the years ended December 31, 2018, 2017 and 2016 were as follows (in millions): 2018 2017 2016 Angola (1) $ 285.7 $ 445.7 $ 552.1 Australia (2) 283.9 206.7 222.8 U.S. Gulf of Mexico (3) 214.7 149.8 531.7 United Kingdom (4) 192.6 164.6 246.2 Saudi Arabia (4) 182.2 171.8 210.6 Brazil (5) 139.6 196.2 298.0 Egypt (5) 31.2 214.8 141.2 Other 375.5 293.4 573.8 $ 1,705.4 $ 1,843.0 $ 2,776.4 (1) For the years ended December 31, 2018, 2017 and 2016 , 86% , 88% and 87% of revenues earned in Angola, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment. (2) For the years ended December 31, 2018, 2017 and 2016 , 92% , 87% and 95% of revenues earned in Australia, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment. (3) For the years ended December 31, 2018, 2017 and 2016 , 30% , 29% and 82% of revenues earned in the U.S. Gulf of Mexico, respectively, were attributable to our Floaters segment, 42% , 31% and 7% of revenues were attributable to our Jackup segment, respectively, and the remaining revenues were attributable to our Other segment, respectively. (4) For the years ended December 31, 2018, 2017 and 2016 , all revenues were attributable to our Jackup segment. (5) For the years ended December 31, 2018, 2017 and 2016 , all revenues were attributable to our Floater segment.

Guarantee Of Registered Secur_2

Guarantee Of Registered Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Guarantees [Abstract]
Condensed Consolidating Statements Of Income	ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 49.5 $ 155.2 $ — $ 1,802.8 $ (302.1 ) $ 1,705.4 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 51.0 139.5 — 1,431.0 (302.1 ) 1,319.4 Loss on impairment — — — 40.3 — 40.3 Depreciation — 14.2 — 464.7 — 478.9 General and administrative 46.3 .4 — 56.0 — 102.7 OPERATING INCOME (LOSS) (47.8 ) 1.1 — (189.2 ) — (235.9 ) OTHER INCOME (EXPENSE), NET 2.7 (135.2 ) (89.0 ) (109.0 ) 27.5 (303.0 ) LOSS FROM CONTINUING OPERATIONS BEFORE INCOME TAXES (45.1 ) (134.1 ) (89.0 ) (298.2 ) 27.5 (538.9 ) INCOME TAX EXPENSE — 43.3 — 46.3 — 89.6 DISCONTINUED OPERATIONS, NET — — — (8.1 ) — (8.1 ) EQUITY EARNINGS (LOSSES) IN AFFILIATES, NET OF TAX (594.6 ) 121.8 93.3 — 379.5 — NET INCOME (LOSS) (639.7 ) (55.6 ) 4.3 (352.6 ) 407.0 (636.6 ) NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (3.1 ) — (3.1 ) NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (639.7 ) $ (55.6 ) $ 4.3 $ (355.7 ) $ 407.0 $ (639.7 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 52.9 $ 163.3 $ — $ 1,941.2 $ (314.4 ) $ 1,843.0 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 50.0 149.9 — 1,304.0 (314.4 ) 1,189.5 Loss on impairment — — — 182.9 — 182.9 Depreciation — 15.9 — 428.9 — 444.8 General and administrative 45.4 50.8 — 61.6 — 157.8 OPERATING LOSS (42.5 ) (53.3 ) — (36.2 ) — (132.0 ) OTHER INCOME (EXPENSE), NET (6.8 ) (110.5 ) (71.7 ) 110.5 14.5 (64.0 ) INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES (49.3 ) (163.8 ) (71.7 ) 74.3 14.5 (196.0 ) INCOME TAX EXPENSE — 45.0 — 64.2 — 109.2 DISCONTINUED OPERATIONS, NET — — — 1.0 — 1.0 EQUITY EARNINGS (LOSSES) IN AFFILIATES, NET OF TAX (254.4 ) 129.6 84.2 — 40.6 — NET INCOME (LOSS) (303.7 ) (79.2 ) 12.5 11.1 55.1 (304.2 ) NET LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — .5 — .5 NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (303.7 ) $ (79.2 ) $ 12.5 $ 11.6 $ 55.1 $ (303.7 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING REVENUES $ 27.9 $ 144.4 $ — $ 2,897.4 $ (293.3 ) $ 2,776.4 OPERATING EXPENSES Contract drilling (exclusive of depreciation) 27.3 144.8 .1 1,422.1 (293.3 ) 1,301.0 Depreciation — 17.2 .4 427.7 — 445.3 General and administrative 36.2 .2 — 64.4 — 100.8 OPERATING INCOME (LOSS) (35.6 ) (17.8 ) (0.5 ) 983.2 — 929.3 OTHER INCOME (EXPENSE), NET 152.9 (79.0 ) (76.6 ) 7.8 63.1 68.2 INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES 117.3 (96.8 ) (77.1 ) 991.0 63.1 997.5 INCOME TAX EXPENSE (BENEFIT) — .7 (.6 ) 108.4 — 108.5 DISCONTINUED OPERATIONS, NET — — — 8.1 — 8.1 EQUITY EARNINGS IN AFFILIATES, NET OF TAX 772.9 205.7 125.7 — (1,104.3 ) — NET INCOME 890.2 108.2 49.2 890.7 (1,041.2 ) 897.1 NET INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (6.9 ) — (6.9 ) NET INCOME ATTRIBUTABLE TO ENSCO $ 890.2 $ 108.2 $ 49.2 $ 883.8 $ (1,041.2 ) $ 890.2
Schedule of Condensed Consolidated Statements of Comprehensive Income	ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME (LOSS) $ (639.7 ) $ (55.6 ) $ 4.3 $ (352.6 ) $ 407.0 $ (636.6 ) OTHER COMPREHENSIVE LOSS, NET Net change in fair value of derivatives — (9.7 ) — — — (9.7 ) Reclassification of net gains on derivative instruments from other comprehensive loss into net loss — (1.0 ) — — — (1.0 ) Other — — — (.5 ) — (.5 ) NET OTHER COMPREHENSIVE LOSS — (10.7 ) — (.5 ) — (11.2 ) COMPREHENSIVE INCOME (LOSS) (639.7 ) (66.3 ) 4.3 (353.1 ) 407.0 (647.8 ) COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (3.1 ) — (3.1 ) COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (639.7 ) $ (66.3 ) $ 4.3 $ (356.2 ) $ 407.0 $ (650.9 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME (LOSS) $ (303.7 ) $ (79.2 ) $ 12.5 $ 11.1 $ 55.1 $ (304.2 ) OTHER COMPREHENSIVE INCOME, NET Net change in fair value of derivatives — 8.5 — — — 8.5 Reclassification of net losses on derivative instruments from other comprehensive income into net income — .4 — — — .4 Other — — — .7 — .7 NET OTHER COMPREHENSIVE INCOME — 8.9 — .7 — 9.6 COMPREHENSIVE INCOME (LOSS) (303.7 ) (70.3 ) 12.5 11.8 55.1 (294.6 ) COMPREHENSIVE LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — .5 — .5 COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO $ (303.7 ) $ (70.3 ) $ 12.5 $ 12.3 $ 55.1 $ (294.1 ) ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-Guarantor Subsidiaries of Ensco Consolidating Adjustments Total NET INCOME $ 890.2 $ 108.2 $ 49.2 $ 890.7 $ (1,041.2 ) $ 897.1 OTHER COMPREHENSIVE INCOME (LOSS), NET Net change in fair value of derivatives — (5.4 ) — — — (5.4 ) Reclassification of net gains on derivative instruments from other comprehensive income into net loss — 12.4 — — — 12.4 Other — — — (.5 ) — (.5 ) NET OTHER COMPREHENSIVE INCOME (LOSS) — 7.0 — (.5 ) — 6.5 COMPREHENSIVE INCOME 890.2 115.2 49.2 890.2 (1,041.2 ) 903.6 COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS — — — (6.9 ) — (6.9 ) COMPREHENSIVE INCOME ATTRIBUTABLE TO ENSCO $ 890.2 $ 115.2 $ 49.2 $ 883.3 $ (1,041.2 ) $ 896.7
Condensed Consolidating Balance Sheets	ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total ASSETS CURRENT ASSETS Cash and cash equivalents $ 199.8 $ — $ 2.7 $ 72.6 $ — $ 275.1 Short-term investments 329.0 — — — — 329.0 Accounts receivable, net 7.3 25.4 — 312.0 — 344.7 Accounts receivable from affiliates 1,861.2 171.4 — 131.7 (2,164.3 ) — Other .6 6.0 — 354.3 — 360.9 Total current assets 2,397.9 202.8 2.7 870.6 (2,164.3 ) 1,309.7 PROPERTY AND EQUIPMENT, AT COST 1.8 125.2 — 15,390.0 — 15,517.0 Less accumulated depreciation 1.8 91.3 — 2,807.7 — 2,900.8 Property and equipment, net — 33.9 — 12,582.3 — 12,616.2 DUE FROM AFFILIATES 2,413.8 234.5 125.0 2,715.1 (5,488.4 ) — INVESTMENTS IN AFFILIATES 8,522.6 3,713.7 1,199.9 — (13,436.2 ) — OTHER ASSETS 8.1 — — 89.7 — 97.8 $ 13,342.4 $ 4,184.9 $ 1,327.6 $ 16,257.7 $ (21,088.9 ) $ 14,023.7 LIABILITIES AND SHAREHOLDERS' EQUITY CURRENT LIABILITIES Accounts payable and accrued liabilities $ 85.3 $ 32.0 $ 12.7 $ 398.5 $ — $ 528.5 Accounts payable to affiliates 59.7 139.5 38.2 1,926.9 (2,164.3 ) — Total current liabilities 145.0 171.5 50.9 2,325.4 (2,164.3 ) 528.5 DUE TO AFFILIATES 1,432.0 1,226.9 1,366.5 1,463.0 (5,488.4 ) — LONG-TERM DEBT 3,676.5 149.3 502.6 682.0 — 5,010.4 OTHER LIABILITIES .1 64.3 — 331.6 — 396.0 ENSCO SHAREHOLDERS' EQUITY (DEFICIT) 8,088.8 2,572.9 (592.4 ) 11,458.3 (13,436.2 ) 8,091.4 NONCONTROLLING INTERESTS — — — (2.6 ) — (2.6 ) Total equity (deficit) 8,088.8 2,572.9 (592.4 ) 11,455.7 (13,436.2 ) 8,088.8 $ 13,342.4 $ 4,184.9 $ 1,327.6 $ 16,257.7 $ (21,088.9 ) $ 14,023.7 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING BALANCE SHEETS December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total ASSETS CURRENT ASSETS Cash and cash equivalents $ 185.2 $ — $ 25.6 $ 234.6 $ — $ 445.4 Short-term investments 440.0 — — — — 440.0 Accounts receivable, net 6.9 .4 — 338.1 — 345.4 Accounts receivable from affiliates 351.8 492.7 — 424.3 (1,268.8 ) — Other — 8.8 — 372.4 — 381.2 Total current assets 983.9 501.9 25.6 1,369.4 (1,268.8 ) 1,612.0 PROPERTY AND EQUIPMENT, AT COST 1.8 120.8 — 15,209.5 — 15,332.1 Less accumulated depreciation 1.8 77.1 — 2,379.5 — 2,458.4 Property and equipment, net — 43.7 — 12,830.0 — 12,873.7 DUE FROM AFFILIATES 3,002.1 2,618.0 165.1 3,736.1 (9,521.3 ) — INVESTMENTS IN AFFILIATES 9,098.5 3,591.9 1,106.6 — (13,797.0 ) — OTHER ASSETS 12.9 5.0 — 226.5 (104.2 ) 140.2 $ 13,097.4 $ 6,760.5 $ 1,297.3 $ 18,162.0 $ (24,691.3 ) $ 14,625.9 LIABILITIES AND SHAREHOLDERS' EQUITY CURRENT LIABILITIES Accounts payable and accrued liabilities $ 55.4 $ 39.0 $ 21.7 $ 642.4 $ — $ 758.5 Accounts payable to affiliates 67.3 458.3 12.4 730.8 (1,268.8 ) — Total current liabilities 122.7 497.3 34.1 1,373.2 (1,268.8 ) 758.5 DUE TO AFFILIATES 1,402.9 3,559.2 753.9 3,805.3 (9,521.3 ) — LONG-TERM DEBT 2,841.8 149.2 1,106.0 653.7 — 4,750.7 OTHER LIABILITIES — 3.1 — 487.8 (104.2 ) 386.7 ENSCO SHAREHOLDERS' EQUITY (DEFICIT) 8,730.0 2,551.7 (596.7 ) 11,844.1 (13,797.0 ) 8,732.1 NONCONTROLLING INTERESTS — — — (2.1 ) — (2.1 ) Total equity (deficit) 8,730.0 2,551.7 (596.7 ) 11,842.0 (13,797.0 ) 8,730.0 $ 13,097.4 $ 6,760.5 $ 1,297.3 $ 18,162.0 $ (24,691.3 ) $ 14,625.9
Condensed Consolidating Statements Of Cash Flows	ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2018 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ 18.1 $ (135.1 ) $ (97.6 ) $ 158.9 $ — $ (55.7 ) INVESTING ACTIVITIES Maturities of short-term investments 1,030.0 — — — — 1,030.0 Purchases of short-term investments (919.0 ) — — — — (919.0 ) Purchase of affiliate debt (551.7 ) — — — 551.7 — Sale of affiliate debt 479.0 — — — (479.0 ) — Additions to property and equipment — — — (426.7 ) — (426.7 ) Net proceeds from disposition of assets — — 11.0 — 11.0 Net cash provided by (used in) investing activities of continuing operations 38.3 — — (415.7 ) 72.7 (304.7 ) FINANCING ACTIVITIES Proceeds from issuance of senior notes 1,000.0 — — — — 1,000.0 Advances from (to) affiliates (845.0 ) 135.1 612.5 97.4 — — Reduction of long-term borrowings (159.9 ) — (537.8 ) (0.8 ) (72.7 ) (771.2 ) Cash dividends paid (17.9 ) — — — — (17.9 ) Debt issuance costs (17.0 ) — — — — (17.0 ) Other (2.0 ) — — (3.7 ) — (5.7 ) Net cash provided by (used in) financing activities (41.8 ) 135.1 74.7 92.9 (72.7 ) 188.2 Net cash provided by discontinued operations — — — 2.5 — 2.5 Effect of exchange rate changes on cash and cash equivalents — — — (.6 ) — (.6 ) NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS 14.6 — (22.9 ) (162.0 ) — (170.3 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 185.2 — 25.6 234.6 — 445.4 CASH AND CASH EQUIVALENTS, END OF YEAR $ 199.8 $ — $ 2.7 $ 72.6 $ — $ 275.1 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2017 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ (18.2 ) $ (117.6 ) $ (100.1 ) $ 495.3 $ — $ 259.4 INVESTING ACTIVITIES Purchases of short-term investments (1,022.9 ) — — (17.1 ) — (1,040.0 ) Maturities of short-term investments 1,748.0 5.5 — 289.0 — 2,042.5 Additions to property and equipment — — — (536.7 ) — (536.7 ) Net proceeds from disposition of assets — — — 2.8 — 2.8 Purchase of affiliate debt (316.3 ) — — — 316.3 — Acquisition of Atwood, net of cash acquired — — — (871.6 ) — (871.6 ) Net cash provided by (used in) investing activities of continuing operations 408.8 5.5 — (1,133.6 ) 316.3 (403.0 ) FINANCING ACTIVITIES Reduction of long-term borrowings (220.7 ) — — — (316.3 ) (537.0 ) Debt issuance costs (12.0 ) — — — — (12.0 ) Cash dividends paid (13.8 ) — — — — (13.8 ) Advances from (to) affiliates (848.9 ) 112.1 105.9 630.9 — — Other (2.6 ) — — (5.1 ) — (7.7 ) Net cash provided by (used in) financing activities (1,098.0 ) 112.1 105.9 625.8 (316.3 ) (570.5 ) Net cash used in discontinued operations — — — (.8 ) — (.8 ) Effect of exchange rate changes on cash and cash equivalents — — — .6 — .6 NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS (707.4 ) — 5.8 (12.7 ) — (714.3 ) CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 892.6 — 19.8 247.3 — 1,159.7 CASH AND CASH EQUIVALENTS, END OF YEAR $ 185.2 $ — $ 25.6 $ 234.6 $ — $ 445.4 ENSCO PLC AND SUBSIDIARIES CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (in millions) Ensco plc ENSCO International Incorporated Pride International LLC Other Non-guarantor Subsidiaries of Ensco Consolidating Adjustments Total OPERATING ACTIVITIES Net cash provided by (used in) operating activities of continuing operations $ (101.3 ) $ (46.5 ) $ (116.9 ) $ 1,342.1 $ — $ 1,077.4 INVESTING ACTIVITIES Purchases of short-term investments (2,047.1 ) (5.5 ) — (422.0 ) — (2,474.6 ) Additions to property and equipment — — — (322.2 ) — (322.2 ) Maturities of short-term investments 2,062.0 — — 150.0 — 2,212.0 Net proceeds from disposition of assets — — — 9.8 — 9.8 Purchase of affiliate debt (237.9 ) — — — 237.9 — Net cash used in investing activities of continuing operations (223.0 ) (5.5 ) — (584.4 ) 237.9 (575.0 ) FINANCING ACTIVITIES Proceeds from debt issuance — — — 849.5 — 849.5 Reduction of long-term borrowing (626.0 ) — — — (237.9 ) (863.9 ) Proceeds from equity issuance 585.5 — — — — 585.5 Cash dividends paid (11.6 ) — — — — (11.6 ) Debt issuance costs (23.4 ) — — — — (23.4 ) Advances from (to) affiliates 1,200.6 52.0 134.7 (1,387.3 ) — — Other (2.2 ) — — (4.9 ) — (7.1 ) Net cash provided by (used in) financing activities 1,122.9 52.0 134.7 (542.7 ) (237.9 ) 529.0 Net cash provided by discontinued operations — — — 8.4 — 8.4 Effect of exchange rate changes on cash and cash equivalents — — — (1.4 ) — (1.4 ) NET INCREASE IN CASH AND CASH EQUIVALENTS 798.6 — 17.8 222.0 — 1,038.4 CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR 94.0 — 2.0 25.3 — 121.3 CASH AND CASH EQUIVALENTS, END OF YEAR $ 892.6 $ — $ 19.8 $ 247.3 $ — $ 1,159.7

Unaudited Quarterly Financial_2

Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Summary Of Unaudited Quarterly Consolidated Income Statement	The following tables summarize our unaudited quarterly condensed consolidated income statement data for the years ended December 31, 2018 and 2017 (in millions, except per share amounts): 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Year Operating revenues $ 417.0 $ 458.5 $ 430.9 $ 399.0 $ 1,705.4 Operating expenses Contract drilling (exclusive of depreciation) 325.2 344.3 327.1 322.8 1,319.4 Loss on impairment (1) — — — 40.3 40.3 Depreciation 115.2 120.7 120.6 122.4 478.9 General and administrative 27.9 26.1 25.1 23.6 102.7 Operating loss (51.3 ) (32.6 ) (41.9 ) (110.1 ) (235.9 ) Other expense, net (70.7 ) (84.8 ) (77.7 ) (69.8 ) (303.0 ) Loss from continuing operations before income taxes (122.0 ) (117.4 ) (119.6 ) (179.9 ) (538.9 ) Income tax expense 18.4 24.7 23.3 23.2 89.6 Loss from continuing operations (140.4 ) (142.1 ) (142.9 ) (203.1 ) (628.5 ) Loss from discontinued operations, net (.1 ) (8.0 ) — — (8.1 ) Net loss (140.5 ) (150.1 ) (142.9 ) (203.1 ) (636.6 ) Net (income) loss attributable to noncontrolling interests .4 (.9 ) (2.1 ) (.5 ) (3.1 ) Net loss attributable to Ensco $ (140.1 ) $ (151.0 ) $ (145.0 ) $ (203.6 ) $ (639.7 ) Loss per share – basic and diluted Continuing operations $ (.32 ) $ (.33 ) $ (.33 ) $ (.47 ) $ (1.45 ) Discontinued operations — (.02 ) — — (.02 ) $ (.32 ) $ (.35 ) $ (.33 ) $ (.47 ) $ (1.47 ) (1) Fourth quarter included an aggregate loss of $40.3 million associated with the impairment of an older, non-core jackup rig. See "Note 5 - Property and Equipment" for additional information. 2017 First Quarter Second Quarter Third Quarter Fourth Quarter Year Operating revenues $ 471.1 $ 457.5 $ 460.2 $ 454.2 $ 1,843.0 Operating expenses Contract drilling (exclusive of depreciation) (1) 278.1 291.3 285.8 334.3 1,189.5 Loss on impairment (2) — — — 182.9 182.9 Depreciation 109.2 107.9 108.2 119.5 444.8 General and administrative (3) 26.0 30.5 30.4 70.9 157.8 Operating income (loss) 57.8 27.8 35.8 (253.4 ) (132.0 ) Other income (expense), net (4) (57.7 ) (53.2 ) (40.4 ) 87.3 (64.0 ) Income (loss) from continuing operations before income taxes .1 (25.4 ) (4.6 ) (166.1 ) (196.0 ) Income tax expense (5) 24.1 19.3 23.4 42.4 109.2 Loss from continuing operations (24.0 ) (44.7 ) (28.0 ) (208.5 ) (305.2 ) Income (loss) from discontinued operations, net (.6 ) .4 (.2 ) 1.4 1.0 Net loss (24.6 ) (44.3 ) (28.2 ) (207.1 ) (304.2 ) Net (income) loss attributable to noncontrolling interests (1.1 ) (1.2 ) 2.8 — .5 Net loss attributable to Ensco $ (25.7 ) $ (45.5 ) $ (25.4 ) $ (207.1 ) $ (303.7 ) Loss per share – basic and diluted Continuing operations $ (.09 ) $ (.15 ) $ (.08 ) $ (.49 ) $ (.91 ) Discontinued operations — — — — — $ (.09 ) $ (.15 ) $ (.08 ) $ (.49 ) $ (.91 ) (1) Fourth quarter included $7.0 million of integration costs associated with the Atwood Merger. See "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations" in Part II for additional information. (2) Fourth quarter included an aggregate loss of $182.9 million associated with the impairment of certain rigs. See "Note 5 - Property and Equipment" for additional information. (3) Fourth quarter included integration costs of $30.9 million and merger-related costs consisting of various advisory, legal, accounting, valuation and other professional or consulting fees totaling $11.5 million . See "Note 3 - Acquisition of Atwood" for additional information. (4) Fourth quarter included a bargain purchase gain of $140.2 million related to the Atwood Merger. See "Note 3 - Acquisition of Atwood" for additional information. (5) Fourth quarter included net discrete tax expense of $16.5 million in connection with enactment of U.S. tax reform. See "Note 10 - Income taxes" for additional information.

Description Of The Business A_4

Description Of The Business And Summary Of Significant Accounting Policies (Narrative) (Details)

Feb. 11, 2019USD ($)$ / sharesshares

Jan. 29, 2019shares

Oct. 07, 2018shares

Jan. 01, 2018USD ($)

Oct. 06, 2017USD ($)

Oct. 05, 2017USD ($)shares

Dec. 31, 2018USD ($)continentcountry

Sep. 30, 2018USD ($)

Jun. 30, 2018USD ($)

Mar. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Mar. 31, 2016USD ($)shares

Sep. 30, 2018USD ($)

Dec. 31, 2018USD ($)continentcountryshares

Sep. 30, 2018USD ($)

Dec. 31, 2017USD ($)shares

Dec. 31, 2016USD ($)

Jan. 01, 2019USD ($)

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

56

Number of different countries having drilling contracts spanning | country

14

14

Number of different continents having drilling contracts | continent

6

6

Bargain purchase gain

$ 142,000,000

$ 1,800,000

$ 140,200,000

$ 0

Net foreign currency exchange gains (losses)

$ (6,000,000)

(17,200,000)

(5,100,000)

Short-term Investments

$ 329,000,000

$ 440,000,000

329,000,000

440,000,000

Asset Impairment Charges

$ 40,300,000

$ 0

$ 0

$ 0

$ 182,900,000

$ 0

$ 0

$ 0

$ 40,300,000

$ 182,900,000

$ 0

Antidilutive share options excluded from computation of diluted earnings per share | shares

500,000

1,500,000

2,000,000

Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings

$ 800,000

Three Percent Senior Notes Due Two Thousand Twenty Four [Member] | Senior Notes [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Debt instrument, interest rate, stated percentage

3.00%

3.00%

Rowan Companies [Member] | Common Class A [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Entity shares issued per acquiree share | shares

2.215

Atwood Oceanics, Inc.

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

4

Consideration transferred

$ 770,700,000

$ 781,800,000

781,800,000

Cash settlement for business acquisitions

11,100,000

Cash and cash equivalents

445,400,000

$ 445,400,000

$ 445,400,000

$ 445,400,000

Payments to extinguish acquiree liabilities

$ 1,300,000,000

Bargain purchase gain

$ 140,200,000

$ 1,800,000

Atwood Oceanics, Inc. | Common Class A [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Entity shares issued per acquiree share | shares

1.60

Number of ordinary shares | shares

132,200,000

Ultra Deepwater Drillships [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

12

Semisubmersible Rigs [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

9

Moored Semisubmersible Rigs [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

3

Moored Semisubmersible Rigs [Member] | Atwood Oceanics, Inc.

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

2

Jackup Rigs [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

35

Jackup Rigs [Member] | Atwood Oceanics, Inc.

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

5

Construction in Progress [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

3

Construction in Progress [Member] | Atwood Oceanics, Inc.

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of contract drilling rigs

2

Drilling rigs and equipment [Member] | Minimum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

4 years

Drilling rigs and equipment [Member] | Maximum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

35 years

Drilling rigs and equipment [Member] | Atwood Oceanics, Inc. | Minimum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

30 years

16 years

Drilling rigs and equipment [Member] | Atwood Oceanics, Inc. | Maximum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

35 years

35 years

Building and Building Improvements [Member] | Minimum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

7 years

Building and Building Improvements [Member] | Maximum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

30 years

Equipment [Member] | Minimum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

3 years

Equipment [Member] | Maximum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment, Useful Life

6 years

Scenario, Forecast [Member] | Rowan Companies [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Consideration transferred

$ 1,500,000,000

Business Acquisition, Share Price | $ / shares

$ 4.41

Scenario, Forecast [Member] | Rowan Companies [Member] | Common Class A [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Number of ordinary shares | shares

351,000,000

Accounting Standards Update 2016-02 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] | Scenario, Forecast [Member] | Minimum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Operating Lease, Liability

$ 75,000,000

Operating Lease, Right-of-Use Asset

65,000,000

Accounting Standards Update 2016-02 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] | Scenario, Forecast [Member] | Maximum [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Operating Lease, Liability

80,000,000

Operating Lease, Right-of-Use Asset

$ 70,000,000

Subsequent Event [Member] | Rowan Companies [Member] | Common Class A [Member]

Description Of The Business And Summary Of Significant Accounting Policies [Line Items]

Entity shares issued per acquiree share | shares

2.750

Description Of The Business A_5

Description Of The Business And Summary Of Significant Accounting Policies (Schedule Of Income From Continuing Operations Attributable To Ensco) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Income (loss) from continuing operations attributable to Ensco	$ (631.6)	$ (304.7)	$ 882.1
Income from continuing operations allocated to non-vested share awards	(0.5)	(0.4)	(16.6)
Income (loss) from continuing operations attributable to Ensco shares	$ (632.1)	$ (305.1)	$ 865.5

Description Of The Business A_6

Description Of The Business And Summary Of Significant Accounting Policies New Accounting Pronouncements or Changes in Accounting Principle (Narrative) (Details)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings	$ 800,000

Revenue from Contracts with C_2

Revenue from Contracts with Customers Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue, Performance Obligation, Description of Timing	The remaining duration of our drilling contracts based on those in place as of December 31, 2018 was between approximately one month and four years.
Capitalized Contract Cost, Net	$ 37.1
ENSCO DS-9 [Member]
Disaggregation of Revenue [Line Items]
Gain (Loss) on Contract Termination		$ 185
ENSCO 8503 [Member]
Disaggregation of Revenue [Line Items]
Gain (Loss) on Contract Termination			$ 20
Upfront Rig Mobilizations And Certain Contract Preparation [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	23.5	40.6
Capitalized Contract Cost, Amortization	34	28.1	42.5
Deferred Certification Costs [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	13.6	15.3
Capitalized Contract Cost, Amortization	$ 12.4	$ 12.1	$ 16.8

Revenue from Contracts with C_3

Revenue from Contracts with Customers Components of Contract Assets and Contract Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset, Net, Current	$ 4	$ 3
Contract with Customer, Asset, Net, Noncurrent	0	2.8
Contract with Customer, Liability, Current	56.9	71.9
Contract with Customer, Liability, Noncurrent	20.5	$ 51.2
Change in Contract With Customer, Asset [Roll Forward]
Contract with Customer, Asset, Net	5.8
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress	2.2
Contract with Customer, Asset, Reclassified to Receivable	(4)
Contract with Customer, Asset, Net	4
Change in Contract With Customer, Liability [Roll Forward]
Contract with Customer, Liability	123.1
Contract with Customer, Liability, Increase from Cash Receipts	49.4
Contract with Customer, Liability, Revenue Recognized, Included In Beginning Balance	(72)
Contract with Customer, Liability, Revenue Recognized, Added During Period	(23.1)
Contract with Customer, Liability	$ 77.4

Revenue from Contracts with C_4

Revenue from Contracts with Customers Future Amortization of Contract Liabilities and Deferred Costs (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 77.4
Capitalized Contract Cost, Amortization Expense, Next Fiscal Year	23.8
Capitalized Contract Cost, Amortization Expense, Year Two	9.4
Capitalized Contract Cost, Amortization Expense, Year Three	2.4
Capitalized Contract Cost, Net	37.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 57
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 11.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 7.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1.5
Capitalized Contract Cost, Amortization Expense, Year Four and Thereafter	$ 1.5

Acquisition Of Atwood Narrative

Acquisition Of Atwood Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 06, 2017	Oct. 05, 2017	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018	May 26, 2017
Business Acquisition [Line Items]
Shares Issued, Price Per Share									$ 9.25
Bargain purchase gain				$ 142	$ 1.8		$ 140.2	$ 0
Merger related costs			$ 11.5
Number of contract drilling rigs					56
Intangible liabilities					$ 60
Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Common stock, value (in usd per share)		$ 9.33
Cash settlement for business acquisitions		$ 11.1
Consideration transferred	$ 770.7	781.8		781.8
Cash and cash equivalents	445.4			445.4		$ 445.4
Payments to extinguish acquiree liabilities		$ 1,300
Bargain purchase gain	140.2					1.8
Merger related costs							19.4
Number of contract drilling rigs					4
Property and equipment	1,762			$ 1,771.2		$ 1,771.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	2.5
Intangible assets acquired	$ 30.1
Asset amortization					$ 11.4		$ 16.1
Intangible assets, net			$ 2.6		$ 2.6
Atwood Oceanics, Inc. | Class A Ordinary Shares, U.S. [Member]
Business Acquisition [Line Items]
Entity shares issued per acquiree share		1.60
Shares Issued, Price Per Share		$ 5.83
Number of ordinary shares		132,200,000
Share Price										$ 6.70
Construction in Progress [Member]
Business Acquisition [Line Items]
Number of contract drilling rigs					3
Construction in Progress [Member] | Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Number of contract drilling rigs					2
Moored Semisubmersible Rigs [Member]
Business Acquisition [Line Items]
Number of contract drilling rigs					3
Moored Semisubmersible Rigs [Member] | Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Number of contract drilling rigs					2
Jackup Rigs [Member]
Business Acquisition [Line Items]
Number of contract drilling rigs					35
Jackup Rigs [Member] | Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Number of contract drilling rigs					5
Minimum [Member] | Drilling rigs and equipment [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life					4 years
Minimum [Member] | Drilling rigs and equipment [Member] | Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life	30 years				16 years
Maximum [Member] | Drilling rigs and equipment [Member]
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life					35 years
Maximum [Member] | Drilling rigs and equipment [Member] | Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Property, Plant and Equipment, Useful Life	35 years				35 years

Acquisition Of Atwood Assets Ac

Acquisition Of Atwood Assets Acquired Liabilities Assumed (Details) - USD ($) $ in Millions	Oct. 06, 2017	Oct. 05, 2017	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Liabilities:
Repayment of Atwood debt(2)		$ (1,305.9)	$ (1,305.9)
Bargain purchase gain			142	$ 1.8		$ 140.2	$ 0
Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Payments to extinguish acquiree liabilities		1,300
Business Combination, Acquired Receivables, Gross Contractual Amount	$ 64.7
Assets:
Cash and cash equivalents	445.4		445.4		$ 445.4
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Cash And Cash Equivalents					0
Accounts Receivable	62.3		60.7		60.7
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Receivable					(1.6)
Other current assets	118.1		122.7		122.7
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Current Assets					4.6
Property and equipment	1,762		1,771.2		1,771.2
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment					9.2
Other assets	23.7		18.6		18.6
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Assets					(5.1)
Liabilities:
Accounts payable and accrued liabilities	64.9		63.8		63.8
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Payable And Accrued Liabilities					(1.1)
Other liabilities	118.7		125.1		125.1
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Other Liabilities					6.4
Net assets acquired	2,227.9		2,229.7		2,229.7
Merger consideration	(770.7)	$ (781.8)	$ (781.8)
Bargain purchase gain	$ 140.2				$ 1.8

Acquisition Of Atwood Pro Forma

Acquisition Of Atwood Pro Forma (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 06, 2017	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2018	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Earnings per share - basic and diluted (in usd per share)		$ (0.47)	$ (0.33)	$ (0.35)	$ (0.32)	$ (0.49)	$ (0.08)	$ (0.15)	$ (0.09)		$ (1.47)		$ (0.91)	$ 3.13
Merger-related costs, excluded from revenue and EPS											$ 80.7
Bargain purchase gain										$ 142	$ 1.8		$ 140.2	$ 0
Atwood Oceanics, Inc.
Business Acquisition [Line Items]
Revenues													2,226	3,622.1
Net income (loss)													$ (347)	$ 1,284.9
Earnings per share - basic and diluted (in usd per share)													$ (0.80)	$ 3.18
Bargain purchase gain	$ 140.2											$ 1.8

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Executive Retirement Plans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in unrealized gains (losses) included in other income	$ (700,000)	$ 4,500,000	$ 1,800,000

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Supplemental executive retirement plan assets	$ 27.2	$ 30.9
Total financial assets	27.2	37.7
Derivative Assets (Liabilities), at Fair Value, Net	(10.7)	6.8
Total Financial Liabilities	(10.7)
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Supplemental executive retirement plan assets	27.2	30.9
Total financial assets	27.2	30.9
Derivative Assets (Liabilities), at Fair Value, Net	0	0
Total Financial Liabilities	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Supplemental executive retirement plan assets	0	0
Total financial assets	0	6.8
Derivative Assets (Liabilities), at Fair Value, Net	(10.7)	6.8
Total Financial Liabilities	(10.7)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Supplemental executive retirement plan assets	0	0
Total financial assets	0	0
Derivative Assets (Liabilities), at Fair Value, Net	0	$ 0
Total Financial Liabilities	$ 0

Fair Value Measurements (Sche_2

Fair Value Measurements (Schedule Of Carrying Values And Estimated Fair Values Of Debt Instruments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 5,010.4	$ 4,750.7
Debt instrument, Fair Value Disclosure		3,545.8	4,271.8
8.50% Senior notes due 2019(1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		0	251.4
Debt instrument, Fair Value Disclosure		$ 0	252.9
Debt instrument, interest rate, stated percentage		8.50%
Senior Note Maturity Year		2,019
6.875% Senior notes due 2020(1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 127.5	477.9
Debt instrument, Fair Value Disclosure		$ 121.6	473.1
Debt instrument, interest rate, stated percentage		6.875%
Senior Note Maturity Year		2,020
4.70% Senior notes due 2021(1)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 112.7	267.1
Debt instrument, Fair Value Disclosure		$ 101.8	265.3
Debt instrument, interest rate, stated percentage		4.70%
Senior Note Maturity Year		2,021
3.00% Exchangeable senior notes due 2024(2)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt instrument, interest rate, stated percentage		3.00%
Senior Note Maturity Year		2,024
3.00% Exchangeable senior notes due 2024(2) | Convertible Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 666.8	635.7
Convertible Debt, Fair Value Disclosures	[1]	575.5	757.1
3.00% exchangeable senior notes, excluding discount and net of debt issuance costs		$ 836.3	834
Debt instrument, interest rate, stated percentage		8.00%
Senior Note Maturity Year		2,024
4.50% Senior notes due 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 619.8	619.3
Debt instrument, Fair Value Disclosure		$ 405.2	527.1
Debt instrument, interest rate, stated percentage		4.50%
Senior Note Maturity Year		2,024
8.00% Senior notes due 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 337	337.9
Debt instrument, Fair Value Disclosure		$ 273.7	333.8
Debt instrument, interest rate, stated percentage		8.00%
Senior Note Maturity Year		2,024
5.20% Senior notes due 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 664.4	663.6
Debt instrument, Fair Value Disclosure		$ 443.9	571.4
Debt instrument, interest rate, stated percentage		5.20%
Senior Note Maturity Year		2,025
7.75% Senior notes due 2026
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 985	0
Debt instrument, Fair Value Disclosure		725.5	0
7.20% Senior notes due 2027
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		149.3	149.3
Debt instrument, Fair Value Disclosure		$ 109.1	141.9
Debt instrument, interest rate, stated percentage		7.20%
Senior Note Maturity Year		2,027
7.875% Senior notes due 2040
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 375	376.7
Debt instrument, Fair Value Disclosure		$ 223.2	258.8
Debt instrument, interest rate, stated percentage		7.875%
Senior Note Maturity Year		2,040
5.75% Senior notes due 2044
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument Carrying Value		$ 972.9	971.8
Debt instrument, Fair Value Disclosure		$ 566.3	$ 690.4
Debt instrument, interest rate, stated percentage		5.75%
Senior Note Maturity Year		2,044
[1]	Our 3.00% exchangeable senior notes due 2024 (the "2024 Convertible Notes") were issued with a conversion feature. The 2024 Convertible Notes were separated into their liability and equity components on our consolidated balance sheet. The equity component was initially recorded to additional paid-in capital and as a debt discount, which will be amortized to interest expense. Excluding the unamortized discount, the carrying value of the 2024 Convertible Notes was $836.3 million and $834.0 million as of December 31, 2018 and 2017. See "Note 6 - Debt" for additional information on this issuance.

Property And Equipment (Schedul

Property And Equipment (Schedule Of Property And Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment	$ 15,517	$ 15,332.1
Drilling rigs and equipment
Property, Plant and Equipment [Line Items]
Property and equipment	14,542.5	12,272.4
Other
Property, Plant and Equipment [Line Items]
Property and equipment	195.3	183.4
Work in progress
Property, Plant and Equipment [Line Items]
Property and equipment	$ 779.2	$ 2,876.3

Property And Equipment (Narrati

Property And Equipment (Narrative) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)rigs	Dec. 31, 2016USD ($)
Property, Plant and Equipment [Line Items]
Document Period End Date									Dec. 31, 2018
Property and equipment	$ 15,517				$ 15,332.1				$ 15,517	$ 15,332.1
Loss on impairment	40.3	$ 0	$ 0	$ 0	182.9	$ 0	$ 0	$ 0	40.3	$ 182.9	$ 0
Jackup Rigs [Member]
Property, Plant and Equipment [Line Items]
Number Of Drilling Rigs With Impairment | rigs										1
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	779.2				2,876.3				779.2	$ 2,876.3
Construction in Progress [Member] | Ultra Deepwater Drillships [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	416.8				2,000				416.8	2,000
Construction in Progress [Member] | Premium Jackup Rigs [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 352.4				321.6				$ 352.4	321.6
Construction in Progress [Member] | Jackup Rigs [Member]
Property, Plant and Equipment [Line Items]
Property and equipment					$ 423.6					$ 423.6
Moored Semisubmersible Rigs [Member]
Property, Plant and Equipment [Line Items]
Number Of Drilling Rigs With Impairment | rigs										2

Debt (Schedule Of Long-Term Deb

Debt (Schedule Of Long-Term Debt Instruments) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Sep. 30, 2016	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015	Mar. 31, 2018	Mar. 31, 2017
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 5,010.4	$ 4,750.7
Long-term Debt, Excluding Current Maturities				5,010.4	4,750.7
8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 0	$ 251.4
Debt instrument, interest rate, stated percentage				8.50%
Senior Note Maturity Year				2,019
8.50% Senior notes due 2019(1) | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			8.50%
Senior Note Maturity Year			2,019		2,019
6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 127.5	$ 477.9
Debt instrument, interest rate, stated percentage				6.875%
Senior Note Maturity Year				2,020
6.875% Senior notes due 2020(1) | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			6.875%
Senior Note Maturity Year		2,020	2,020
4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 112.7	267.1
Debt instrument, interest rate, stated percentage				4.70%
Senior Note Maturity Year				2,021
4.70% Senior notes due 2021(1) | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			4.70%
Senior Note Maturity Year		2,021	2,021
3.00% Exchangeable senior notes due 2024(2)
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				3.00%
Senior Note Maturity Year				2,024
3.00% Exchangeable senior notes due 2024(2) | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 666.8	635.7
Debt instrument, interest rate, stated percentage				8.00%
Senior Note Maturity Year				2,024
3.00% exchangeable senior notes, excluding discount and net of debt issuance costs				$ 836.3	834
4.50% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 619.8	619.3
Debt instrument, interest rate, stated percentage				4.50%
Senior Note Maturity Year				2,024
4.50% Senior notes due 2024 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						4.50%
Senior Note Maturity Year						2,024
8.00% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 337	$ 337.9
Debt instrument, interest rate, stated percentage				8.00%
Senior Note Maturity Year				2,024
8.00% Senior notes due 2024 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				8.00%	8.00%
Senior Note Maturity Year				2,024	2,024
5.20% Senior notes due 2025
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 664.4	$ 663.6
Debt instrument, interest rate, stated percentage				5.20%
Senior Note Maturity Year				2,025
5.20% Senior notes due 2025 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				5.20%
Senior Note Maturity Year				2,025
7.75% Senior notes due 2026
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 985	0
7.75% Senior notes due 2026 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage							7.75%
7.20% Senior notes due 2027
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 149.3	$ 149.3
Debt instrument, interest rate, stated percentage				7.20%
Senior Note Maturity Year				2,027
7.20% Senior notes due 2027 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage					7.20%
7.875% Senior notes due 2040
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 375	$ 376.7
Debt instrument, interest rate, stated percentage				7.875%
Senior Note Maturity Year				2,040
7.875% Senior notes due 2040 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage			7.875%
Senior Note Maturity Year			2,040
5.75% Senior notes due 2044
Debt Instrument [Line Items]
Debt Instrument Carrying Value				$ 972.9	$ 971.8
Debt instrument, interest rate, stated percentage				5.75%
Senior Note Maturity Year				2,044
5.75% Senior notes due 2044 | Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						5.75%		5.75%
Senior Note Maturity Year	2,044					2,044

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Sep. 30, 2016	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2018	Feb. 28, 2018	Feb. 09, 2018	Feb. 07, 2018	Oct. 31, 2017	Sep. 30, 2017	Jan. 05, 2017
Debt Instrument [Line Items]
Document Period End Date								Dec. 31, 2018
Tender Offer								$ 985,000,000
Debt Instrument, Repurchased Face Amount								721,800,000
Extinguishment of Debt, Gain (Loss), Net of Tax		$ 19,000,000
Debt Instrument, Repurchase Amount								771,200,000
Stock Issued During Period, Shares, New Issues	65,550,000		1,822,432						1,822,432
Gain (Loss) on Extinguishment of Debt				$ 6,200,000				(19,000,000)	$ (2,600,000)	$ 287,800,000
Interest Expense								282,700,000	224,200,000	228,800,000
Capitalized interest								$ 62,600,000	$ 72,500,000	45,700,000
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage									0.00%
Debentures Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage									0.00%
3.00% Exchangeable senior notes due 2024(2)
Debt Instrument [Line Items]
Senior Note Maturity Year								2,024
Debt instrument, interest rate, stated percentage								3.00%
5.20% Senior notes due 2025
Debt Instrument [Line Items]
Senior Note Maturity Year								2,025
Debt instrument, interest rate, stated percentage								5.20%
5.75% Senior notes due 2044
Debt Instrument [Line Items]
Senior Note Maturity Year								2,044
Debt instrument, interest rate, stated percentage								5.75%
4.50% Senior notes due 2024
Debt Instrument [Line Items]
Senior Note Maturity Year								2,024
Debt instrument, interest rate, stated percentage								4.50%
4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Senior Note Maturity Year								2,021
Debt instrument, interest rate, stated percentage								4.70%
6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Senior Note Maturity Year								2,020
Debt instrument, interest rate, stated percentage								6.875%
Debt Instrument, Repurchased Face Amount								$ 328,000,000
Debt Instrument, Repurchase Amount								$ 354,700,000
8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Senior Note Maturity Year								2,019
Debt instrument, interest rate, stated percentage								8.50%
Debt Instrument, Repurchased Face Amount								$ 237,600,000
Debt Instrument, Repurchase Amount								$ 256,800,000
7.875% Senior notes due 2040
Debt Instrument [Line Items]
Senior Note Maturity Year								2,040
Debt instrument, interest rate, stated percentage								7.875%
7.20% Senior notes due 2027
Debt Instrument [Line Items]
Senior Note Maturity Year								2,027
Debt instrument, interest rate, stated percentage								7.20%
8.00% Senior notes due 2024
Debt Instrument [Line Items]
Senior Note Maturity Year								2,024
Debt instrument, interest rate, stated percentage								8.00%
Open Market Repurchases [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								$ 194,100,000
Debt Instrument, Repurchase Amount								204,500,000
Revolving Credit Facility [Member] | Five Year Credit Facility Member
Debt Instrument [Line Items]
Current borrowing capacity			$ 2,000,000,000					2,000,000,000	$ 2,000,000,000							$ 2,250,000,000
Potential_Additional_Revolver_Capacity								$ 1,500,000,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage									0.75%
Maximum Percent of Debt to Total Capitalization Ratio								60.00%
Line of Credit Facility, Fair Value of Amount Outstanding			0						$ 0
Debt Covenant, Additional Secured Debt, Value								$ 750,000,000
Debt Covenant, Additional Secured Debt, Percent Of Tangible Net Worth								10.00%
Common Stock, Dividends, Per Share, Cash Paid								$ 0.01
Debt Covenant, Aggregate Amount Of Available Cash								$ 150,000,000
Revolving Credit Facility [Member] | Credit Facility due 2020 [Member]
Debt Instrument [Line Items]
Current borrowing capacity								1,300,000,000								$ 1,130,000,000
Revolving Credit Facility [Member] | Credit Facility due 2019 [Member]
Debt Instrument [Line Items]
Current borrowing capacity								$ 1,200,000,000
Debt Covenant, Period For Repayment Of Acquired Companies								90 days
Debt Covenant, Aggregate Amount Of Available Cash, After Repayments								$ 250,000,000
Revolving Credit Facility [Member] | Base Rate [Member] | Five Year Credit Facility Member
Debt Instrument [Line Items]
Basis spread on variable rate									3.00%
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Five Year Credit Facility Member
Debt Instrument [Line Items]
Basis spread on variable rate									4.00%
Convertible Debt [Member] | 3.00% Exchangeable senior notes due 2024(2)
Debt Instrument [Line Items]
Interest Expense, Debt, Excluding Amortization								25,500,000	$ 25,500,000
Amortization of Debt Issuance Costs and Discounts								31,000,000	31,400,000
Debt Instrument, Face Amount			849,500,000					$ 849,500,000	849,500,000
Senior Note Maturity Year								2,024
Conversion rate per $1,000 principal amount of shares								71.3343
Debt Instrument, Convertible, Conversion Price								$ 14.02
Debt instrument, interest rate, stated percentage								8.00%
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount																	$ 194,100,000
Debt Instrument, Repurchase Amount																	204,500,000
Senior Notes [Member] | 7.75% Senior notes due 2026
Debt Instrument [Line Items]
Debt Instrument, Face Amount												$ 1,000,000,000
Debt instrument, interest rate, stated percentage		7.75%
Senior Notes [Member] | 5.20% Senior notes due 2025
Debt Instrument [Line Items]
Debt Instrument, Face Amount										$ 700,000,000
Senior Note Maturity Year								2,025
Debt instrument, interest rate, stated percentage								5.20%
Debt Instrument, Unamortized Discount (Premium), Net				2,600,000
Senior Notes [Member] | 5.75% Senior notes due 2044
Debt Instrument [Line Items]
Debt Instrument, Face Amount				$ 400,000,000							$ 625,000,000
Senior Note Maturity Year					2,044						2,044
Debt instrument, interest rate, stated percentage				5.75%							5.75%
Debt Instrument, Unamortized Discount (Premium), Net				$ 18,700,000							$ 2,800,000
Debt Instrument, Repurchased Face Amount			24,500,000						24,500,000
Gain (Loss) on Extinguishment of Debt									8,800,000
Senior Notes [Member] | 4.50% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument, Face Amount											$ 625,000,000
Senior Note Maturity Year											2,024
Debt instrument, interest rate, stated percentage											4.50%
Debt Instrument, Unamortized Discount (Premium), Net											$ 850,000
Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 1,500,000,000
Senior Note Maturity Year						2,021	2,021
Debt instrument, interest rate, stated percentage							4.70%
Debt Instrument, Unamortized Discount (Premium), Net							$ 29,600,000
Debt Instrument, Repurchased Face Amount		$ 156,200,000	413,300,000					$ 156,200,000	413,300,000								39,400,000
Debt Instrument, Repurchase Amount		159,700,000															39,300,000
Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 900,000,000
Senior Note Maturity Year						2,020	2,020
Debt instrument, interest rate, stated percentage							6.875%
Debt Instrument, Repurchased Face Amount			229,900,000					328,000,000	$ 229,900,000				$ 71,400,000		$ 256,600,000		100,100,000
Debt Instrument, Repurchase Amount																	105,100,000
Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 500,000,000
Senior Note Maturity Year							2,019		2,019
Debt instrument, interest rate, stated percentage							8.50%
Debt Instrument, Repurchased Face Amount			200,400,000					237,600,000	$ 200,400,000				$ 55,000,000	$ 182,600,000			54,600,000
Debt Instrument, Repurchase Amount																	$ 60,100,000
Senior Notes [Member] | 7.875% Senior notes due 2040
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 300,000,000
Senior Note Maturity Year							2,040
Debt instrument, interest rate, stated percentage							7.875%
Senior Notes [Member] | 7.20% Senior notes due 2027
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 150,000,000						$ 150,000,000
Debt instrument, interest rate, stated percentage			7.20%						7.20%
Senior Notes [Member] | 8.00% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument, Face Amount			$ 332,000,000					$ 332,000,000	$ 332,000,000
Senior Note Maturity Year								2,024	2,024
Debt instrument, interest rate, stated percentage			8.00%					8.00%	8.00%
Exchange Offers [Member]
Debt Instrument [Line Items]
Amortization of Debt Discount (Premium)		3,500,000
Amortization of Debt Issuance Costs		$ 2,700,000
Exchange Offers [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount																		$ 649,500,000
Debt Instrument, Repurchase Amount																		664,500,000
Exchange Offers [Member] | Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount																		373,900,000
Debt Instrument, Repurchase Amount																		362,500,000
Exchange Offers [Member] | Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount																		129,800,000
Debt Instrument, Repurchase Amount																		138,700,000
Exchange Offers [Member] | Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount																		145,800,000
Debt Instrument, Repurchase Amount																		163,300,000
Exchange Offers [Member] | Senior Notes [Member] | 8.00% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument, Face Amount																		$ 332,000,000

Debt (Schedule of Convertible D

Debt (Schedule of Convertible Debt) (Details) - Convertible Debt [Member] - 3.00% Exchangeable senior notes due 2024(2) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 849.5	$ 849.5
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	(182.7)	(213.8)
Convertible Debt	666.8	635.7
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 220	$ 220

Debt (Schedule of Extinguishmen

Debt (Schedule of Extinguishment of Debt - Tender and OMR) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Mar. 31, 2018	Feb. 28, 2018	Feb. 09, 2018	Feb. 07, 2018	Dec. 31, 2017	Sep. 30, 2017
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	$ 721.8
Debt Instrument, Repurchase Amount	771.2
8.50% Senior notes due 2019(1)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	237.6
Debt Instrument, Repurchase Amount	256.8
6.875% Senior notes due 2020(1)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	328
Debt Instrument, Repurchase Amount	354.7
Senior Notes [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount							$ 194.1
Debt Instrument, Repurchase Amount							204.5
Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	237.6		$ 55	$ 182.6		$ 200.4	54.6
Debt Instrument, Repurchase Amount							60.1
Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	328		$ 71.4		$ 256.6	229.9	100.1
Debt Instrument, Repurchase Amount							105.1
Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	$ 156.2	$ 156.2				$ 413.3	39.4
Debt Instrument, Repurchase Amount		$ 159.7					$ 39.3

Debt (Schedule of Extinguishm_2

Debt (Schedule of Extinguishment of Debt - Exchange Offers) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Mar. 31, 2018	Feb. 28, 2018	Feb. 09, 2018	Feb. 07, 2018	Dec. 31, 2017	Sep. 30, 2017	Jan. 05, 2017	Dec. 31, 2012
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	$ 721.8
Debt Instrument, Repurchase Amount	771.2
8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	237.6
Debt Instrument, Repurchase Amount	256.8
6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	328
Debt Instrument, Repurchase Amount	354.7
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount							$ 194.1
Debt Instrument, Repurchase Amount							204.5
Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	237.6		$ 55	$ 182.6		$ 200.4	54.6
Debt Instrument, Face Amount									$ 500
Debt Instrument, Repurchase Amount							60.1
Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	328		$ 71.4		$ 256.6	229.9	100.1
Debt Instrument, Face Amount									900
Debt Instrument, Repurchase Amount							105.1
Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	156.2	$ 156.2				413.3	39.4
Debt Instrument, Face Amount									$ 1,500
Debt Instrument, Repurchase Amount		$ 159.7					$ 39.3
Senior Notes [Member] | 8.00% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 332					$ 332
Exchange Offers [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Amount Paid in Cash								$ 332.5
Exchange Offers [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Amount Paid in Cash								81.7
Exchange Offers [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Amount Paid in Cash								69.4
Exchange Offers [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Amount Paid in Cash								181.4
Exchange Offers [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								649.5
Debt Instrument, Repurchase Amount								664.5
Exchange Offers [Member] | Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								145.8
Debt Instrument, Repurchase Amount								163.3
Exchange Offers [Member] | Senior Notes [Member] | 8.50% senior notes due 2019 exchanged for 8.00% senior notes due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								81.6
Exchange Offers [Member] | Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								129.8
Debt Instrument, Repurchase Amount								138.7
Exchange Offers [Member] | Senior Notes [Member] | 6.875% Senior notes due 2020 exchanged for 8.00% Senior notes due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								69.3
Exchange Offers [Member] | Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								373.9
Debt Instrument, Repurchase Amount								362.5
Exchange Offers [Member] | Senior Notes [Member] | 4.70% senior notes due 2021 exchanged for 8.00% senior notes due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount								181.1
Exchange Offers [Member] | Senior Notes [Member] | 8.00% Senior notes due 2024
Debt Instrument [Line Items]
Debt Instrument, Face Amount								$ 332

(Aggregate Maturities Of Long-T

(Aggregate Maturities Of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Feb. 28, 2018	Feb. 09, 2018	Feb. 07, 2018	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2012
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	$ 721.8
Long-Term Debt, Gross	5,161						$ 6,549.5
8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	237.6
6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	328
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount								$ 194.1
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										$ (1,155.1)
Debt Instrument, Repurchased Face Amount Net of Exchanged Notes							(511.6)
Debt Instrument, Repurchased Face Amount Net of Debt Issuance	278.2
Senior Notes [Member] | 8.50% Senior notes due 2019(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	237.6			$ 55	$ 182.6		200.4	54.6
Long-Term Debt, Maturities, Repayments of Principal in Year Three							500
Long-Term Debt, Maturities, Repayments of Principal in Year Four	0
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										(62)
Debt Instrument, Face Amount												$ 500
Senior Notes [Member] | 6.875% Senior notes due 2020(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	328			$ 71.4		$ 256.6	229.9	100.1
Long-Term Debt, Maturities, Repayments of Principal in Year Four							900
Long-Term Debt, Maturities, Repayments of Principal in Year Five	122.9
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										(219.2)
Debt Instrument, Face Amount												900
Senior Notes [Member] | 4.70% Senior notes due 2021(1)
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	156.2		$ 156.2				413.3	$ 39.4
Long-Term Debt, Maturities, Repayments of Principal in Year Five							1,500
Long-Term Debt, Maturities, Repayments of Principal after Year Five	113.5
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										(817)
Debt Instrument, Face Amount												1,500
Senior Notes [Member] | 4.50% Senior notes due 2024
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	623.3						625
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										(1.7)
Debt Instrument, Face Amount											$ 625
Senior Notes [Member] | 8.00% Senior notes due 2024
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	332						0
Debt Instrument, Face Amount	332						332
Senior Notes [Member] | 5.20% Senior notes due 2025
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	669.3						700
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										(30.7)
Debt Instrument, Face Amount										700
Senior Notes [Member] | 7.75% Senior notes due 2026
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	1,000						0
Debt Instrument, Face Amount		$ 1,000
Senior Notes [Member] | 7.20% Senior notes due 2027
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	150						150
Debt Instrument, Face Amount							150
Senior Notes [Member] | 7.875% Senior notes due 2040
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	300						300
Debt Instrument, Face Amount												$ 300
Senior Notes [Member] | 5.75% Senior notes due 2044
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount							24.5
Long-Term Debt, Maturities, Repayments of Principal after Year Five	1,000.5						1,025
Face (Par) Amount of the Original Debt Instrument, Including Repurchases and Equity Exchanges										$ (24.5)
Debt Instrument, Face Amount									$ 400		$ 625
Convertible Debt [Member] | 3.00% Exchangeable senior notes due 2024(2)
Debt Instrument [Line Items]
Long-Term Debt, Maturities, Repayments of Principal after Year Five	849.5						849.5
Debt Instrument, Face Amount	$ 849.5						$ 849.5

Derivative Instruments (Narrati

Derivative Instruments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ (10.7)	$ 6.8
Maximum maturity period for all derivatives	18 months
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gains on derivatives not designated as hedging instruments	$ (11.8)	10	$ (7)
Foreign Currency Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(10.7)	$ 6.8
Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	187.8
Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	175.7
United Kingdom, Pounds | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	88
United Kingdom, Pounds | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	10.2
Australia, Dollars | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	50.3
Australia, Dollars | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	19.8
Euro Member Countries, Euro | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	19.7
Euro Member Countries, Euro | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	89.3
Brazil, Brazil Real | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	16.2
Brazil, Brazil Real | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	19.6
Singapore, Dollars | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	11
No currency | Foreign Exchange Forward [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	2.6
No currency | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	26.5
Indonesia, Rupiahs | Foreign Exchange Forward [Member] | Fair Value Hedging [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 10.3

Derivative Instruments (Schedul

Derivative Instruments (Schedule Of Derivatives At Fair Value) (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Total fair value of derivative assets		$ 0.6	$ 7.3
Total fair value of derivative liabilities		11.3	0.5
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total fair value of derivative assets		0.2	6.4
Total fair value of derivative liabilities		8.7	0.3
Designated as Hedging Instrument [Member] | Foreign Currency Forward Contracts - Current [Member]
Derivative [Line Items]
Total fair value of derivative assets	[1]	0.2	5.9
Total fair value of derivative liabilities	[1]	8.3	0.2
Designated as Hedging Instrument [Member] | Foreign Currency Forward Contracts - Non-Current [Member]
Derivative [Line Items]
Total fair value of derivative assets		0	0.5
Total fair value of derivative liabilities		0.4	0.1
Not Designated as Hedging Instrument [Member] | Foreign Currency Forward Contracts - Current [Member]
Derivative [Line Items]
Total fair value of derivative assets	[1]	0.4	0.9
Total fair value of derivative liabilities	[1]	$ 2.6	$ 0.2
[1]	Derivative assets and liabilities that have maturity dates equal to or less than 12 months from the respective balance sheet dates were included in other current assets and accrued liabilities and other, respectively, on our consolidated balance sheets.

Derivative Instruments (Gains A

Derivative Instruments (Gains And Losses On Derivatives Designated As Cash Flow Hedges) (Details) - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		$ 5,400,000	$ (9,700,000)	$ (8,500,000)
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)		12,400,000	(1,000,000)	400,000
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)		1,900,000	(1,900,000)	(700,000)
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Lock Contracts [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[1]	0	0	0
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	[1],[2]	200,000	200,000	200,000
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	[1],[3]	0	0	0
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	[4]		(9,700,000)	8,500,000	$ (5,400,000)
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)	[2],[4]		(1,200,000)	200,000	12,200,000
Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	[3],[4]		(1,900,000)	(700,000)	$ 1,900,000
Derivative, Notional Amount			187,800,000
Contract Drilling [Member] | Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)		(13,100,000)	400,000	(1,100,000)
Depreciation Expense [Member] | Foreign Currency Forward Contracts [Member]
Derivative [Line Items]
Gain (Loss) Reclassified from AOCI into Income (Effective Portion)		$ 900,000	$ 800,000	$ 900,000
[1]	Losses on interest rate lock derivatives reclassified from AOCI into income were included in interest expense, net, in our consolidated statements of operations.
[2]	Changes in the fair value of cash flow hedges are recorded in AOCI. Amounts recorded in AOCI associated with cash flow hedges are subsequently reclassified into contract drilling, depreciation or interest expense as earnings are affected by the underlying hedged forecasted transaction.
[3]	Gains and losses recognized in income for amounts excluded from effectiveness testing were included in other, net, in our consolidated statements of operations.
[4]	During the year ended December 31, 2018, $400,000 of gains were reclassified from AOCI into contract drilling expense and $800,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2017, $1.1 million of losses were reclassified from AOCI into contract drilling expense and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations. During the year ended December 31, 2016, $13.1 million of losses were reclassified from AOCI into contract drilling and $900,000 of gains were reclassified from AOCI into depreciation expense in our consolidated statement of operations.

Derivative Instruments (Sched_2

Derivative Instruments (Schedule Of Estimated Amount Of Net Gains Associated With Derivatives) (Details) $ in Millions	Dec. 31, 2018USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net unrealized gains to be reclassified to contract drilling expense	$ (5.2)
Net realized gains to be reclassified to depreciation expense	0.8
Net realized (losses) to be reclassified to interest expense	(0.2)
Net gains to be reclassified to earnings	$ (4.6)

Shareholders' Equity (Schedule

Shareholders' Equity (Schedule Of Activity In Our Various Shareholders' Equity) (Details) - USD ($) $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				$ 8,730						$ 8,730
Net income (loss)	$ (203.1)	$ (142.9)	$ (150.1)	$ (140.5)	$ (207.1)	$ (28.2)	$ (44.3)	$ (24.6)		(636.6)	$ (304.2)	$ 897.1
Stock Issued During Period, Shares, New Issues			65,550,000		1,822,432						1,822,432
Net other comprehensive income (loss)										(11.2)	$ 9.6	$ 6.5
BALANCE	$ 8,088.8				$ 8,730					$ 8,088.8	$ 8,730
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE, shares				447,000,000				310,300,000	242,900,000	447,000,000	310,300,000	242,900,000
BALANCE				$ 44.8				$ 31.1	$ 24.4	$ 44.8	$ 31.1	$ 24.4
Stock Issued During Period, Shares, New Issues											132,200,000	65,600,000
Stock Issued During Period, Value, New Issues											$ 13.2	$ 6.5
Shares Issued Under Share Based Compensation Plans, Shares										13,700,000	4,500,000
Conversion of Stock, Shares Issued												1,800,000
Conversion of Stock, Amount Issued												$ 0.2
Shares issued under share-based compensation plans, net										$ 1.4	$ 0.5
BALANCE, shares	460,700,000				447,000,000					460,700,000	447,000,000	310,300,000
BALANCE	$ 46.2				$ 44.8					$ 46.2	$ 44.8	$ 31.1
Additional Paid-In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				7,195				6,402.2	5,554.5	7,195	6,402.2	5,554.5
Stock Issued During Period, Value, New Issues											757.5	579
Conversion of Stock, Amount Issued												14.8
Debt Instrument, Convertible, Carrying Amount of Equity Component												220
Shares issued under share-based compensation plans, net										(0.6)	(0.4)
Tax benefit (deficiency) from share-based compensation									(3.4)
Repurchase of shares										0
Share-based compensation cost									37.3	30.6	35.7
BALANCE	7,225				7,195					7,225	7,195	6,402.2
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				1,532.7				1,864.1	985.3	1,532.7	1,864.1	985.3
Net income (loss)									890.2	(639.7)	(303.7)
Cash dividends paid									(11.4)	(18)	(13.6)
BALANCE	874.2				1,532.7					874.2	1,532.7	1,864.1
AOCI [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				28.6				19	12.5	28.6	19	12.5
Net other comprehensive income (loss)									6.5	(11.2)	9.6
BALANCE	18.2				28.6					18.2	28.6	19
Treasury Shares [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				(69)				(65.8)	(63.8)	(69)	(65.8)	(63.8)
Shares issued under share-based compensation plans, net										(1.3)	(1.3)
Repurchase of shares									(2)	(1.9)	(1.9)
BALANCE	(72.2)				(69)					(72.2)	(69)	(65.8)
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
BALANCE				$ (2.1)				4.4	4.3	(2.1)	4.4	4.3
Net income (loss)									6.9	3.1	(0.5)
Distributions to noncontrolling interests									$ (7.8)	(3.6)	(6)
Proceeds from Noncontrolling Interests												1
BALANCE	$ (2.6)				$ (2.1)					(2.6)	(2.1)	$ 4.4
Accounting Standards Update 2016-16 [Member] | Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification											$ (14.1)
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-16 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification								$ (14.1)
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-16 [Member] | Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										(0.8)
New Accounting Pronouncement, Early Adoption, Effect [Member] | Accounting Standards Update 2016-16 [Member] | AOCI [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										$ 0.8

Shareholders' Equity (Share Iss

Shareholders' Equity (Share Issuance Narrative) (Details) - USD ($)	Oct. 06, 2017	Oct. 05, 2017	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2017	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Shares Issuance [Line Items]
Document Period End Date							Dec. 31, 2018
Shares Issued, Price Per Share			$ 9.25
Stock Issued During Period, Shares, New Issues			65,550,000	1,822,432				1,822,432
Proceeds from (Repurchase of) Equity			$ 585,500,000
Debt Instrument, Repurchased Face Amount							$ 721,800,000
Gain (Loss) on Extinguishment of Debt					$ 6,200,000		(19,000,000)	$ (2,600,000)	$ 287,800,000
Stock Repurchase Program, Authorized Amount				$ 2,000,000,000			$ 500,000,000	$ 2,000,000,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased				35,000,000			65,000,000	35,000,000
Stock Repurchased During Period, Shares								0
Atwood Oceanics, Inc.
Shares Issuance [Line Items]
Business Combination, Consideration Transferred	$ 770,700,000	$ 781,800,000				$ 781,800,000
Class A Ordinary Shares, U.S. [Member] | Atwood Oceanics, Inc.
Shares Issuance [Line Items]
Number of ordinary shares		132,200,000
Shares Issued, Price Per Share		$ 5.83
Senior Notes [Member]
Shares Issuance [Line Items]
Debt Instrument, Repurchased Face Amount										$ 194,100,000
Senior Notes [Member] | 5.75% Senior notes due 2044
Shares Issuance [Line Items]
Debt Instrument, Repurchased Face Amount				$ 24,500,000				$ 24,500,000
Gain (Loss) on Extinguishment of Debt								$ 8,800,000
Maximum [Member]
Shares Issuance [Line Items]
Common Stock, Shares Authorized							145,600,000
Maximum [Member] | Private Placement [Member]
Shares Issuance [Line Items]
Common Stock, Shares Authorized							291,200,000

Benefit Plans (Narrative) (Deta

Benefit Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 25.46
Long-Term Incentive Plan (LTIP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized	59,000,000
Shares reserved for issuance as awards	34,000,000
Share Options Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost on awards	$ 0
Share options award, outstanding	691,852
Non-Vested Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost on awards	$ 63,500
Recognized compensation cost, weighted-average period, years	3 years 6 months
Non-Vested Share Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share awards, vest rate	33.00%
Non-Vested Share Awards [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share awards, vest rate	20.00%
Non-Vested Share Awards, Liability Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period	114,000
Non Vested Share Awards, Equity Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period	6,298,000
Exercisable In Increments Over Three-Year Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share awards, vest rate	33.00%
Exercisable In Increments Over Four-Year Period [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share awards, vest rate	25.00%
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost on awards	$ 10,300
Recognized compensation cost, weighted-average period, years		1 year 10 months 24 days
Share option awards, exercisable, increment	3 years
Performance awards, granted, aggregate grant-date fair value	$ 6,700	$ 6,700	$ 6,100
Performance awards, vested, aggregate fair value	700	2,900	2,800
Recognized compensation expense	$ 8,200	8,400	3,100
Savings Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance as awards	1,000,000
Share awards, vest rate	33.00%
Share option awards, exercisable, increment	3 years
Employee match	100.00%
Total matching contributions	$ 14,400	$ 12,200	16,700
Profit sharing contribution provisions			$ 19,200
Savings Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of eligible employee compensation to be matched by employer	5.00%
Atwood Oceanics, Inc. | Long-Term Incentive Plan (LTIP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance as awards	1,400,000

Benefit Plans (Summary Of Non-V

Benefit Plans (Summary Of Non-Vested Share Award Related Compensation Expense Recognized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Tax benefit	$ (2.8)	$ (4.8)	$ (5.9)
Total non-vested share award related compensation expense included in net income	30.6	28	30.6
Contract Drilling [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Non-vested share award related compensation expense	18.9	18.3	19.9
General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Non-vested share award related compensation expense	14.5	14.5	16.6
Operating Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Non-vested share award related compensation expense	$ 33.4	$ 32.8	$ 36.5

Benefit Plans (Summary Of Value

Benefit Plans (Summary Of Value Of Non-Vested Share Awards Granted And Vested) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non Vested Share Awards, Equity Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of non-vested share awards granted (per share)	$ 6.16	$ 7.90	$ 10.42
Total fair value of non-vested share awards vested during the period (in millions)	$ 7.5	$ 8.6	$ 8.8
Non-Vested Share Awards, Liability Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of non-vested share awards granted (per share)	$ 5.31	$ 6.27	$ 9.64
Total fair value of non-vested share awards vested during the period (in millions)	$ 9.9	$ 3.9	$ 0

Benefit Plans (Summary Of Non_2

Benefit Plans (Summary Of Non-Vested Share Award Activity) (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Non Vested Share Awards, Equity Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share awards and cash-settled awards as of December 31, 2017	3,305
Non-vested Granted, Shares	6,298
Non-vested Vested, Shares	(1,312)
Non-vested Forfeited, Shares	(225)
Share awards and cash-settled awards as of December 31, 2018	8,066	3,305
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested as of December 31, 2016, Weighted-Average Grant-Date Fair Value	$ 16.06
Non-vested Granted, Weighted-Average Grant-Date Fair Value	6.16	$ 7.90	$ 10.42
Non-vested Vested, Weighted-Average Grant-Date Fair Value	19.85
Non-vested Forfeited, Weighted-Average Grant-Date Fair Value	11.62
Non-vested as of December 31, 2017, Weighted-Average Grant-Date Fair Value	$ 7.84	$ 16.06
Non-Vested Share Awards, Liability Classified [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Share awards and cash-settled awards as of December 31, 2017	7,089
Non-vested Granted, Shares	114
Non-vested Vested, Shares	(1,512)
Non-vested Forfeited, Shares	(574)
Share awards and cash-settled awards as of December 31, 2018	5,117	7,089
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested as of December 31, 2016, Weighted-Average Grant-Date Fair Value	$ 7.37
Non-vested Granted, Weighted-Average Grant-Date Fair Value	5.31	$ 6.27	$ 9.64
Non-vested Vested, Weighted-Average Grant-Date Fair Value	7.53
Non-vested Forfeited, Weighted-Average Grant-Date Fair Value	7.18
Non-vested as of December 31, 2017, Weighted-Average Grant-Date Fair Value	$ 7.30	$ 7.37

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount					$ 46
Income from continuing operations before income taxes in the U.S. countries				$ (151.6)	(115.1)	$ 6.3
Income from continuing operations before income taxes in the non-U.S. countries				$ 1,149	(423.8)	(200)
Tax Cuts and Jobs Act of 2017, Measurement Period Adjustment, Income Tax Expense (Benefit)	$ 11.7
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit)		$ 16.5
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)						16.5
Tax Cuts and Jobs Act of 2017, tax benefit on re-measurement on deferred tax assets and liabilities		38.5
Tax Cuts and Jobs Act of 2017, transition tax		17.3
Tax Cuts and Jobs Act of 2017, Change in Tax Rate, Deferred Tax Liability, Income Tax (Expense) Benefit						20
Tax Cuts and Jobs Act of 2017, tax benefit on valuation allowance						19.3
Deferred tax assets related to U.S. foreign tax credits	123.6	132.3			123.6	132.3
Deferred tax assets related to net operating loss carryforwards	148.4	187.1			148.4	187.1
Net operating loss carryforwards	784.2				$ 784.2
Operating Loss Carryforwards, Limitations on Use					40.2
Operating loss carryforwards, Not subject to expiration	449.8				$ 449.8
Operating loss carryforwards, Subject to expiration	334.4				334.4
Valuation allowance on NOL carryforwards and FTC	271.8				271.8
Income Tax Expense (Benefit), Discrete Item						32.2	$ 8.4
Other discrete income tax expenses					$ 21	$ 15.7
Valuation Allowance, Deferred Tax Asset, Change in Amount							5.5
Unrecognized Tax Benefits Associated with Liabilities for Unrecognized Tax Benefits							$ 5.3
Consilidated effective income tax rate excluding discrete items					(24.80%)	(96.00%)	20.30%
Minimum percentage threshold for recognition of tax benefits					50.00%
Total unrecognized tax benefits	143	147.6			$ 143	$ 147.6	$ 122
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions With Net Operating Loss Carryforwards					6.5	8.2
Amount of unrecognized tax benefits affecting the consolidated effective income tax rate if recognized	127.4				127.4
Amount of accrued interest and penalties included in other liabilities	40.5	38.6			40.5	38.6
Amount of interest and penalties recognized in net tax expense					1.9	4.4	3.8
Income tax benefits, inclusive of interest and penalties due to lapses in statute of limitations	5.3	1.1			$ 5.3	1.1	0.6
Document Period End Date					Dec. 31, 2018
Aggregate Undistributed Earnings of Subsidiaries to be Continually Reinvested	386.7				$ 386.7
Other Liabilities [Member]
Total unrecognized tax benefits	$ 136.5	$ 139.4			$ 136.5	$ 139.4
Minimum [Member]
Deferred Tax Assets, Foreign, Expiration Date					2,022
Operating loss carryforwards tax credits expiration year					2,019
Maximum [Member]
Deferred Tax Assets, Foreign, Expiration Date					2,028
Operating loss carryforwards tax credits expiration year					2,037
Other Operating Income (Expense) [Member]
Income Tax Expense (Benefit), Discrete Item							$ 16.9
Scenario, Forecast [Member]
Decline in unrecognized tax benefits during next twelve months								$ 0.5
Accrued interest and penalty assessments related to the decline in unrecognized tax benefits								$ 0.3
Accounting Standards Update 2016-16 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 14.1

Income Taxes (Summary Of Compon

Income Taxes (Summary Of Components Of Provision For Income Taxes From Continuing Operations) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current income tax expense, U.S.									$ (19.9)	$ (2.2)	$ (6.6)
Current income tax expense, Non-U.S.									52.9	56.4	86.4
Current Income Tax Expense, Total									33	54.2	79.8
Deferred income tax expense (benefit), U.S.									52.9	36	15.9
Deferred income tax expense (benefit), Non-U.S.									3.7	19	12.8
Deferred income tax expense									56.6	55	28.7
Income Tax Expense (Benefit)	$ 23.2	$ 23.3	$ 24.7	$ 18.4	$ 42.4	$ 23.4	$ 19.3	$ 24.1	$ 89.6	$ 109.2	$ 108.5

Income Taxes (Summary Of Signif

Income Taxes (Summary Of Significant Components Of Deferred Income Tax Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Net operating loss carryforwards	$ 148.4	$ 187.1
Foreign tax credits	123.6	132.3
Interest limitation carryforwards	40.2	0
Premiums on long-term debt	23.8	36.1
Employee benefits, including share-based compensation	15.4	20.7
Deferred revenue	10.3	26
Other	14.5	12.8
Total deferred tax assets	376.2	415
Valuation allowance	(316)	(278.8)
Net deferred tax assets	60.2	136.2
Property and equipment	(54.5)	(51.5)
Deferred U.S. tax on foreign income	(31.5)	(24.8)
Deferred costs	(5.3)	(9.1)
Deferred transition tax	0	(13.7)
Other	(3.7)	(8.7)
Total deferred tax liabilities	95	107.8
Total deferred tax liabilities	$ (34.8)
Net deferred tax asset (liability)		$ 28.4

Income Taxes (Summary Of Effect

Income Taxes (Summary Of Effective Income Tax Rate On Continuing Operations) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
U.K. statutory income tax rate	19.00%	19.20%	20.00%
Non-U.K. taxes	(18.00%)	(40.40%)	(7.90%)
Valuation allowance	(16.90%)	(18.00%)	2.60%
Debt repurchases	(1.60%)	(2.80%)	(4.10%)
Asset impairments	(1.40%)	(17.10%)	0.00%
Bargain purchase gain	(0.20%)	13.80%	0.00%
U.S. tax reform	2.20%	(8.40%)	0.00%
Tax restructuring transaction	1.70%	0.00%	0.00%
Other	(1.40%)	(2.00%)	0.30%
Effective income tax rate	(16.60%)	(55.70%)	10.90%

Income Taxes (Summary Of Reconc

Income Taxes (Summary Of Reconciliation Of The Beginning And Ending Amount Of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Balance, beginning of year	$ 147.6	$ 122
Increases in unrecognized tax benefits as a result of tax positions taken during the current year	6.5	5.4
Impact of foreign currency exchange rates	(5)	8.1
Lapse of applicable statutes of limitations	(4.5)	(0.4)
Increases in unrecognized tax benefits as a result of tax positions taken during prior years	2.5	0.7
Decreases in unrecognized tax benefits as a result of tax positions taken during prior years	(3.8)	(0.2)
Settlements with taxing authorities	(0.3)	(10.2)
Increases in unrecognized tax benefits as a result of Atwood acquisition	0	22.2
Balance, end of year	$ 143	$ 147.6

Discontinued Operations (Schedu

Discontinued Operations (Schedule of Rig Sales) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations		$ 2.5	$ (0.8)	$ 8.4
Net Book Value	[1],[2]	6.9
Pre-tax Gain/(Loss)	[2]	2.3
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	[2]	9.2
Floaters [Member] | ENSCO 7500 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations	[2]	2.6
Net Book Value	[1],[2]	1.5
Pre-tax Gain/(Loss)		1.1
Floaters [Member] | ENSCO DS-2 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations	[2]	5
Net Book Value	[1],[2]	4
Pre-tax Gain/(Loss)		1
Floaters [Member] | ENSCO 6000 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations	[2]	0.6
Net Book Value	[1],[2]	0.8
Pre-tax Gain/(Loss)		(0.2)
Jackups [Member] | ENSCO 90 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations	[2]	0.3
Net Book Value	[1],[2]	0.3
Pre-tax Gain/(Loss)		0
Jackups [Member] | ENSCO 58 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net cash provided by (used in) discontinued operations	[2]	0.7
Net Book Value	[1],[2]	0.3
Pre-tax Gain/(Loss)		$ 0.4
[1]	Includes the rig's net book value as well as inventory and other assets on the date of the sale.
[2]	The rigs' operating results were reclassified to discontinued operations in our consolidated statements of operations for each of the years in the three-year period ended December 31, 2018 and were previously included within the specified operating segment.

Discontinued Operations (Summar

Discontinued Operations (Summary Of Income From Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Discontinued Operations and Disposal Groups [Abstract]
Revenues									$ 0	$ 0	$ 0
Operating expenses									3.1	2	1.5
Operating (loss) income before income taxes									(3.1)	(2)	(1.5)
Income tax benefit									(10.1)	7.1	(2.1)
Gain on disposal of discontinued operations, net									1.1	1	0.4
DISCONTINUED OPERATIONS, NET	$ 0	$ 0	$ (8)	$ (0.1)	$ 1.4	$ (0.2)	$ 0.4	$ (0.6)	$ 8.1	$ (8.1)	$ 1	$ 8.1

Discontinued Operations (Narrat

Discontinued Operations (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)rigs	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations, Income Tax Expense (Benefit), Discrete Item | $	$ (6.9)	$ 2.1	$ 10.2
Document Period End Date	Dec. 31, 2018
Jackup Rigs [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number Of Contract Drilling Rigs Sold	12
Semisubmersible Rigs [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number Of Contract Drilling Rigs Sold	5
Moored Semisubmersible Rigs [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number Of Contract Drilling Rigs Sold	1
Ultra Deepwater Drillships [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number Of Contract Drilling Rigs Sold	2

Commitments And Contingencies_2

Commitments And Contingencies (Capital Commitments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Document Period End Date		Dec. 31, 2018
Cumulative Paid	[1]	$ 291.4
Aggregate Contractual Capital Commitments Due In One Year		92.9
Aggregate Contractual Capital Commitments Due In Two Years		165
Aggregate Contractual Capital Commitments Due Thereafter		0
Total	[2]	549.3
ENSCO 123 [Member]
Property, Plant and Equipment [Line Items]
Cumulative Paid	[1]	276.4
Aggregate Contractual Capital Commitments Due In One Year		9
Aggregate Contractual Capital Commitments Due In Two Years		0
Aggregate Contractual Capital Commitments Due Thereafter		0
Total	[2]	285.4
Aggregate Contractual Capital Commitments Paid			$ 207.4
ENSCO DS-14 [Member]
Property, Plant and Equipment [Line Items]
Cumulative Paid	[1]	15
Aggregate Contractual Capital Commitments Due In One Year		0
Aggregate Contractual Capital Commitments Due In Two Years		165
Aggregate Contractual Capital Commitments Due Thereafter		0
Total	[2]	180
ENSCO DS-13 [Member]
Property, Plant and Equipment [Line Items]
Cumulative Paid	[1]	0
Aggregate Contractual Capital Commitments Due In One Year		83.9
Aggregate Contractual Capital Commitments Due In Two Years		0
Aggregate Contractual Capital Commitments Due Thereafter		0
Total	[2]	$ 83.9
[1]	Cumulative paid represents the aggregate amount of contractual payments made from commencement of the construction agreement through December 31, 2018. Contractual payments made by Atwood prior to the Atwood Merger for ENSCO DS-13 and ENSCO DS-14 are excluded.
[2]	Total commitments are based on fixed-price shipyard construction contracts, exclusive of our internal costs associated with project management, commissioning and systems integration testing. Total commitments also exclude holding costs and interest.

Commitments And Contingencies_3

Commitments And Contingencies (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2018	Jan. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Rental expenses			$ 40.1	$ 37	$ 39.7
2,019			32.3
2,020			18.7
2,021			11.9
2,022			9.2
2,023			8.9
Thereafter			15.2
Loss Contingency, Damages Sought, Value	$ 2.8	$ 10
Letters of Credit Outstanding, Amount			$ 126.3

Segment Information (Narrative)

Segment Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018servicesegmentscontract
Segment Reporting Information [Line Items]
Number of operating segments	3
Number of reportable segments	2
Number of services | service	1
Number of contract drilling rigs	56
Number of drilling management contracts | contract	2
Ultra Deepwater Drillships [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	12
Moored Semisubmersible Rigs [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	3
Jackup Rigs [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	35
Floaters [Member] | Ultra Deepwater Drillships [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	10
Floaters [Member] | Dynamically Positioned Semisubmersible [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	9
Floaters [Member] | Moored Semisubmersible Rigs [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	3
Floaters [Member] | Asset under Construction [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	2
Jackups [Member] | Jackup Rigs [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	35
Jackups [Member] | Jackup Rigs Deployed [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	34
Jackups [Member] | Asset under Construction [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs	1

Segment Information (Schedule O

Segment Information (Schedule Of Segment Reporting Information) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)contract	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)contract	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Document Period End Date									Dec. 31, 2018
Number of drilling management contracts | contract	2								2
Revenues	$ 399	$ 430.9	$ 458.5	$ 417	$ 454.2	$ 460.2	$ 457.5	$ 471.1	$ 1,705.4	$ 1,843	$ 2,776.4
Operating expenses - Contract drilling (exclusive of depreciation)	322.8	327.1	344.3	325.2	334.3	285.8	291.3	278.1	1,319.4	1,189.5	1,301
Loss on impairment	40.3	0	0	0	182.9	0	0	0	40.3	182.9	0
Depreciation expense	122.4	120.6	120.7	115.2	119.5	108.2	107.9	109.2	478.9	444.8	445.3
General and administrative	23.6	25.1	26.1	27.9	70.9	30.4	30.5	26	102.7	157.8	100.8
OPERATING INCOME (LOSS)	(110.1)	$ (41.9)	$ (32.6)	$ (51.3)	(253.4)	$ 35.8	$ 27.8	$ 57.8	(235.9)	(132)	929.3
Property and equipment, net	12,616.2				12,873.7				12,616.2	12,873.7	10,919.3
Capital expenditures									426.7	536.7	322.2
Floaters [Member]
Segment Reporting Information [Line Items]
Revenues									1,013.5	1,143.5	1,771.1
Operating expenses - Contract drilling (exclusive of depreciation)									737.4	624.2	725
Loss on impairment									0	174.7
Depreciation expense									311.8	297.4	304.1
General and administrative									0	0	0
OPERATING INCOME (LOSS)									(35.7)	47.2	742
Property and equipment, net	9,465.6				9,650.9				9,465.6	9,650.9	8,300.4
Capital expenditures									105.5	470.3	110.3
Jackups [Member]
Segment Reporting Information [Line Items]
Revenues									630.9	640.3	929.5
Operating expenses - Contract drilling (exclusive of depreciation)									526.5	512.1	516.8
Loss on impairment									40.3	8.2
Depreciation expense									153.3	131.5	123.7
General and administrative									0	0	0
OPERATING INCOME (LOSS)									(89.2)	(11.5)	289
Property and equipment, net	3,114.1				3,177.6				3,114.1	3,177.6	2,561
Capital expenditures									317.7	62.1	206.2
Other [Member]
Segment Reporting Information [Line Items]
Revenues									61	59.2	75.8
Operating expenses - Contract drilling (exclusive of depreciation)									55.5	53.2	59.2
Loss on impairment									0	0
Depreciation expense									0	0	0
General and administrative									0	0	0
OPERATING INCOME (LOSS)									5.5	6	16.6
Property and equipment, net	0				0				0	0	0
Capital expenditures									0	0	0
Operating Segments Total [Member]
Segment Reporting Information [Line Items]
Revenues									1,705.4	1,843	2,776.4
Operating expenses - Contract drilling (exclusive of depreciation)									1,319.4	1,189.5	1,301
Loss on impairment									40.3	182.9
Depreciation expense									465.1	428.9	427.8
General and administrative									0	0	0
OPERATING INCOME (LOSS)									(119.4)	41.7	1,047.6
Property and equipment, net	12,579.7				12,828.5				12,579.7	12,828.5	10,861.4
Capital expenditures									423.2	532.4	316.5
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Operating expenses - Contract drilling (exclusive of depreciation)									0	0	0
Loss on impairment									0	0
Depreciation expense									13.8	15.9	17.5
General and administrative									102.7	157.8	100.8
OPERATING INCOME (LOSS)									(116.5)	(173.7)	(118.3)
Property and equipment, net	$ 36.5				$ 45.2				36.5	45.2	57.9
Capital expenditures									$ 3.5	$ 4.3	$ 5.7

Segment Information (Schedule_2

Segment Information (Schedule Of Geographic Distribution Of Rigs By Segment) (Details)	Dec. 31, 2018rigs
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	59
Floaters [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	24
Jackups [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	35
North & South America (Excluding Brazil) [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	12
North & South America (Excluding Brazil) [Member] | Floaters [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	8
North & South America (Excluding Brazil) [Member] | Jackups [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	4
Europe & Mediterranean [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	18
Europe & Mediterranean [Member] | Floaters [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	7
Europe & Mediterranean [Member] | Jackups [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	11
Middle East & Africa [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	15
Middle East & Africa [Member] | Floaters [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	3
Middle East & Africa [Member] | Jackups [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	12
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	11
Asia Pacific [Member] | Construction in Progress [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	3
Asia Pacific [Member] | Floaters [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	4
Asia Pacific [Member] | Floaters [Member] | Construction in Progress [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	2
Asia Pacific [Member] | Jackups [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	7
Asia Pacific [Member] | Jackups [Member] | Construction in Progress [Member]
Segment Reporting Information [Line Items]
Total number of contract drilling rigs	1

Segment Information (Schedule_3

Segment Information (Schedule Of Long-Lived Assets By Geographical Segment) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Long-lived Assets	$ 12,616.2	$ 12,873.7	$ 10,919.3
Geographic Areas [Member]
Segment Reporting Information [Line Items]
Long-lived Assets	12,616.2	12,873.7	10,919.3
Geographic Areas [Member] | SPAIN
Segment Reporting Information [Line Items]
Long-lived Assets	2,306.6	2,004.2	2,334.5
Geographic Areas [Member] | United States [Member]
Segment Reporting Information [Line Items]
Long-lived Assets	2,270	2,764.9	2,898.3
Geographic Areas [Member] | NIGERIA
Segment Reporting Information [Line Items]
Long-lived Assets	1,368.2	583.3	0
Geographic Areas [Member] | United Kingdom [Member]
Segment Reporting Information [Line Items]
Long-lived Assets	1,185.2	609.4	409
Geographic Areas [Member] | SINGAPORE
Segment Reporting Information [Line Items]
Long-lived Assets	23.9	2,859.3	1,388.4
Geographic Areas [Member] | Other countries [Member]
Segment Reporting Information [Line Items]
Long-lived Assets	$ 5,462.3	$ 4,052.6	$ 3,889.1

Supplemental Financial Inform_3

Supplemental Financial Information (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Segment Reporting Information [Line Items]
Aggregate Contractual Capital Commitments Due In One Year	$ 92.9
Capitalized interest	62.6	$ 72.5	$ 45.7
Capital expenditure accruals	27.8	$ 234.3	$ 11.5
ENSCO 123 [Member]
Segment Reporting Information [Line Items]
Aggregate Contractual Capital Commitments Paid				$ 207.4
Aggregate Contractual Capital Commitments Due In One Year	$ 9

Supplemental Financial Inform_4

Supplemental Financial Information (Accounts Receivable, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Information For Property, Casualty Insurance Underwriters [Line Items]
Accounts receivable	$ 348.1	$ 369
Allowance for doubtful accounts	(3.4)	(23.6)
Accounts receivable, net	344.7	345.4
Trade [Member]
Supplemental Information For Property, Casualty Insurance Underwriters [Line Items]
Accounts receivable	301.7	335.4
Other Credit Derivatives [Member]
Supplemental Information For Property, Casualty Insurance Underwriters [Line Items]
Accounts receivable	$ 46.4	$ 33.6

Supplemental Financial Inform_5

Supplemental Financial Information (Other Current Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Abstract]
Inventory	$ 268.1	$ 278.8
Prepaid taxes	35	43.5
Deferred mobilization costs	23.5	29.7
Prepaid expenses	15.2	14.2
Other	19.1	15
Other current assets	$ 360.9	$ 381.2

Supplemental Financial Inform_6

Supplemental Financial Information (Other Assets, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Abstract]
Deferred tax assets	$ 29.4	$ 38.8
Supplemental executive retirement plan assets	27.2	30.9
Deferred mobilization costs	21.5	37.4
Finite-Lived Intangible Assets, Net	2.5	15.7
Other	17.2	17.4
Other assets, net	$ 97.8	$ 140.2

Supplemental Financial Inform_7

Supplemental Financial Information (Accrued Liabilities And Other) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Abstract]
Accrued interest	$ 100.6	$ 83.1
Personnel costs	82.5	112
Deferred revenue	56.9	71.9
Taxes	36.9	46.4
Derivative Liability	10.9	0.4
Other	30.2	12.1
Accrued liabilities and other	$ 318	$ 325.9

Supplemental Financial Inform_8

Supplemental Financial Information (Other Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Abstract]
Unrecognized tax benefits (inclusive of interest and penalties)	$ 177	$ 178
Deferred Tax Liabilities, Net, Noncurrent	70.7	18.5
Intangible Liabilities Noncurrent	53.5	59.6
Supplemental executive retirement plan liabilities	28.1	32
Personnel costs	25.1	18.1
Deferred revenue	20.5	51.2
Deferred Rent Credit	11.7	17.1
Other Accrued Liabilities, Noncurrent	9.4	12.2
Other liabilities	$ 396	$ 386.7

Supplemental Financial Inform_9

Supplemental Financial Information (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Supplemental Financial Information [Abstract]
Derivative Instruments	$ 12.6	$ 22.5
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	7.3	7.8
Other	(1.7)	(1.7)
Accumulated other comprehensive income	$ 18.2	$ 28.6

Supplemental Financial Infor_10

Supplemental Financial Information (Repair And Maintenance Expense Related To Continuing Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Financial Information [Abstract]
Repair and maintenance expense	$ 198.4	$ 188.7	$ 151.1

Supplemental Financial Infor_11

Supplemental Financial Information (Cash Flows Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Financial Information [Abstract]
(Increase) decrease in accounts receivable	$ (6.2)	$ 83.2	$ 222.4
(Increase) decrease in other assets	(2.8)	(14)	44
(Decrease) increase in liabilities	(9)	(3.8)	(125.8)
Changes in operating assets and liabilities	$ (18)	$ 65.4	$ 140.6

Supplemental Financial Infor_12

Supplemental Financial Information (Cash Paid For Interest And Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Financial Information [Abstract]
Interest, net of amounts capitalized	$ 232.6	$ 199.8	$ 264.8
Income taxes	$ 58.4	$ 62.8	$ 56.4

Supplemental Financial Infor_13

Supplemental Financial Information Supplemental Financial Information (Major Customers) (Details)		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Document Period End Date		Dec. 31, 2018
Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		100.00%	100.00%	100.00%
TOTAL [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	[1]	15.00%	22.00%	13.00%
Saudi Aramco [Member] [Domain] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		11.00%	9.00%	6.00%
Petrobras [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		8.00%	11.00%	9.00%
BP [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	[1]	7.00%	15.00%	12.00%
Other Customers [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		59.00%	43.00%	60.00%
Floaters [Member] | BP [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		27.00%	78.00%	76.00%
Other Rigs [Member] | BP [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		53.00%		17.00%
Jackups Member | BP [Member] | Customer Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage		20.00%		7.00%
[1]	For the years ended December 31, 2018, 2017 and 2016, all Total and Petrobras revenues were attributable to the Floater segment.

Supplemental Financial Infor_14

Supplemental Financial Information Supplemental Financial Information (Revenue by region) (Details) - USD ($) $ in Millions		3 Months Ended									12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues		$ 399	$ 430.9	$ 458.5	$ 417	$ 454.2	$ 460.2	$ 457.5	$ 471.1		$ 1,705.4	$ 1,843	$ 2,776.4
Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues											1,705.4	1,843	2,776.4
Floaters [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues											1,013.5	1,143.5	1,771.1
Jackups Member
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues											630.9	640.3	929.5
Angola [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[1]										$ 285.7	$ 445.7	552.1
Angola [Member] | Floaters [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration Risk, Percentage										87.00%	86.00%	88.00%
AUSTRALIA | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[1]										$ 283.9	$ 206.7	222.8
AUSTRALIA | Floaters [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration Risk, Percentage										95.00%	92.00%	87.00%
Us Gulf Of Mexico [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[2]										$ 214.7	$ 149.8	$ 531.7
Us Gulf Of Mexico [Member] | Floaters [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration Risk, Percentage											30.00%	29.00%	82.00%
Us Gulf Of Mexico [Member] | Jackups Member | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Concentration Risk, Percentage											42.00%	31.00%	7.00%
United Kingdom [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[3]										$ 192.6	$ 164.6	$ 246.2
SAUDI ARABIA | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[1]										182.2	171.8	210.6
Brazil [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[4]										139.6	196.2	298
EGYPT | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	[1]										31.2	214.8	141.2
Other Geographic Areas [Member] | Geographic Concentration Risk [Member] | Sales Revenue, Services, Net [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues											$ 375.5	$ 293.4	$ 573.8
[1]	For the years ended December 31, 2018, 2017 and 2016, 86%, 88% and 87% of revenues earned in Angola, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment.
[2]	For the years ended December 31, 2018, 2017 and 2016, 92%, 87% and 95% of revenues earned in Australia, respectively, were attributable to our Floaters segment with the remaining revenues attributable to our Jackup segment.
[3]	For the years ended December 31, 2018, 2017 and 2016, all revenues were attributable to our Jackup segment.
[4]	For the years ended December 31, 2018, 2017 and 2016, 30%, 29% and 82% of revenues earned in the U.S. Gulf of Mexico, respectively, were attributable to our Floaters segment, 42%, 31% and 7% of revenues were attributable to our Jackup segment, respectively, and the remaining revenues were attributable to our Other segment, respectively.

Guarantee Of Registered Secur_3

Guarantee Of Registered Securities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018USD ($)
Guarantor Obligations [Line Items]
Senior notes aggregate outstanding principal balance	$ 400,000,000
6.875% Senior notes due 2020(1)
Guarantor Obligations [Line Items]
Senior Note Maturity Year	2,020
Debt instrument interest rate stated percentage	6.875%
7.875% Senior Notes Due 2040 [Member]
Guarantor Obligations [Line Items]
Senior Note Maturity Year	2,040
Debt instrument interest rate stated percentage	7.875%
7.20% Senior notes due 2027
Guarantor Obligations [Line Items]
Senior Note Maturity Year	2,027
Debt instrument interest rate stated percentage	7.20%
Notes Issued	$ 150,000,000

Guarantee Of Registered Secur_4

Guarantee Of Registered Securities (Condensed Consolidating Statements Of Income) (Details) - USD ($) $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Revenues	$ 399	$ 430.9	$ 458.5	$ 417	$ 454.2	$ 460.2	$ 457.5	$ 471.1		$ 1,705.4	$ 1,843	$ 2,776.4
Contract drilling (exclusive of depreciation)	322.8	327.1	344.3	325.2	334.3	285.8	291.3	278.1		1,319.4	1,189.5	1,301
Loss on impairment	40.3	0	0	0	182.9	0	0	0		40.3	182.9	0
Depreciation expense	122.4	120.6	120.7	115.2	119.5	108.2	107.9	109.2		478.9	444.8	445.3
General and administrative	23.6	25.1	26.1	27.9	70.9	30.4	30.5	26		102.7	157.8	100.8
OPERATING INCOME (LOSS)	(110.1)	(41.9)	(32.6)	(51.3)	(253.4)	35.8	27.8	57.8		(235.9)	(132)	929.3
OTHER (EXPENSE) INCOME, NET	(69.8)	(77.7)	(84.8)	(70.7)	87.3	(40.4)	(53.2)	(57.7)		(303)	(64)	68.2
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(179.9)	(119.6)	(117.4)	(122)	(166.1)	(4.6)	(25.4)	0.1		(538.9)	(196)	997.5
Total provision for income taxes	23.2	23.3	24.7	18.4	42.4	23.4	19.3	24.1		89.6	109.2	108.5
DISCONTINUED OPERATIONS, NET	0	0	(8)	(0.1)	1.4	(0.2)	0.4	(0.6)	$ 8.1	(8.1)	1	8.1
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										0	0	0
NET INCOME (LOSS)	(203.1)	(142.9)	(150.1)	(140.5)	(207.1)	(28.2)	(44.3)	(24.6)		(636.6)	(304.2)	897.1
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(0.5)	(2.1)	(0.9)	0.4	0	2.8	(1.2)	(1.1)		(3.1)	0.5	(6.9)
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO	$ (203.6)	$ (145)	$ (151)	$ (140.1)	$ (207.1)	$ (25.4)	$ (45.5)	$ (25.7)		(639.7)	(303.7)	890.2
Ensco Plc [Member]
Guarantor Obligations [Line Items]
Revenues										49.5	52.9	27.9
Contract drilling (exclusive of depreciation)										51	50	27.3
Loss on impairment										0	0
Depreciation expense										0	0	0
General and administrative										46.3	45.4	36.2
OPERATING INCOME (LOSS)										(47.8)	(42.5)	(35.6)
OTHER (EXPENSE) INCOME, NET										2.7	(6.8)	152.9
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES										(45.1)	(49.3)	117.3
Total provision for income taxes										0	0	0
DISCONTINUED OPERATIONS, NET										0	0	0
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										(594.6)	(254.4)	772.9
NET INCOME (LOSS)										(639.7)	(303.7)	890.2
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS										0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO										(639.7)	(303.7)	890.2
ENSCO International Inc. [Member]
Guarantor Obligations [Line Items]
Revenues										155.2	163.3	144.4
Contract drilling (exclusive of depreciation)										139.5	149.9	144.8
Loss on impairment										0	0
Depreciation expense										14.2	15.9	17.2
General and administrative										0.4	50.8	0.2
OPERATING INCOME (LOSS)										1.1	(53.3)	(17.8)
OTHER (EXPENSE) INCOME, NET										(135.2)	(110.5)	(79)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES										(134.1)	(163.8)	(96.8)
Total provision for income taxes										43.3	45	0.7
DISCONTINUED OPERATIONS, NET										0	0	0
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										121.8	129.6	205.7
NET INCOME (LOSS)										(55.6)	(79.2)	108.2
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS										0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO										(55.6)	(79.2)	108.2
Pride International Inc. [Member]
Guarantor Obligations [Line Items]
Revenues										0	0	0
Contract drilling (exclusive of depreciation)										0	0	0.1
Loss on impairment										0	0
Depreciation expense										0	0	0.4
General and administrative										0	0	0
OPERATING INCOME (LOSS)										0	0	(0.5)
OTHER (EXPENSE) INCOME, NET										(89)	(71.7)	(76.6)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES										(89)	(71.7)	(77.1)
Total provision for income taxes										0	0	(0.6)
DISCONTINUED OPERATIONS, NET										0	0	0
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										93.3	84.2	125.7
NET INCOME (LOSS)										4.3	12.5	49.2
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS										0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO										4.3	12.5	49.2
Other Non-Guarantor Subsidiaries Of Ensco [Member]
Guarantor Obligations [Line Items]
Revenues										1,802.8	1,941.2	2,897.4
Contract drilling (exclusive of depreciation)										1,431	1,304	1,422.1
Loss on impairment										40.3	182.9
Depreciation expense										464.7	428.9	427.7
General and administrative										56	61.6	64.4
OPERATING INCOME (LOSS)										(189.2)	(36.2)	983.2
OTHER (EXPENSE) INCOME, NET										(109)	110.5	7.8
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES										(298.2)	74.3	991
Total provision for income taxes										46.3	64.2	108.4
DISCONTINUED OPERATIONS, NET										(8.1)	1	8.1
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										0	0	0
NET INCOME (LOSS)										(352.6)	11.1	890.7
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS										(3.1)	0.5	(6.9)
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO										(355.7)	11.6	883.8
Consolidating Adjustments [Member]
Guarantor Obligations [Line Items]
Revenues										(302.1)	(314.4)	(293.3)
Contract drilling (exclusive of depreciation)										(302.1)	(314.4)	(293.3)
Loss on impairment										0	0
Depreciation expense										0	0	0
General and administrative										0	0	0
OPERATING INCOME (LOSS)										0	0	0
OTHER (EXPENSE) INCOME, NET										27.5	14.5	63.1
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES										27.5	14.5	63.1
Total provision for income taxes										0	0	0
DISCONTINUED OPERATIONS, NET										0	0	0
EQUITY EARNINGS IN AFFILIATES, NET OF TAX										379.5	40.6	(1,104.3)
NET INCOME (LOSS)										407	55.1	(1,041.2)
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS										0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO										$ 407	$ 55.1	$ (1,041.2)

Guarantee Of Registered Secur_5

Guarantee Of Registered Securities (Condensed Consolidating Statements Of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
NET INCOME (LOSS)	$ (203.1)	$ (142.9)	$ (150.1)	$ (140.5)	$ (207.1)	$ (28.2)	$ (44.3)	$ (24.6)	$ (636.6)	$ (304.2)	$ 897.1
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									(9.7)	8.5	(5.4)
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									(1)	0.4	12.4
Other									(0.5)	0.7	(0.5)
NET OTHER COMPREHENSIVE INCOME (LOSS)									(11.2)	9.6	6.5
COMPREHENSIVE INCOME (LOSS)									(647.8)	(294.6)	903.6
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									(3.1)	0.5	(6.9)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									(650.9)	(294.1)	896.7
Ensco Plc [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(639.7)	(303.7)	890.2
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									0	0	0
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									0	0	0
Other									0	0	0
NET OTHER COMPREHENSIVE INCOME (LOSS)									0	0	0
COMPREHENSIVE INCOME (LOSS)									(639.7)	(303.7)	890.2
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									(639.7)	(303.7)	890.2
ENSCO International Inc. [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(55.6)	(79.2)	108.2
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									(9.7)	8.5	(5.4)
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									(1)	0.4	12.4
Other									0	0	0
NET OTHER COMPREHENSIVE INCOME (LOSS)									(10.7)	8.9	7
COMPREHENSIVE INCOME (LOSS)									(66.3)	(70.3)	115.2
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									(66.3)	(70.3)	115.2
Pride International Inc. [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									4.3	12.5	49.2
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									0	0	0
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									0	0	0
Other									0	0	0
NET OTHER COMPREHENSIVE INCOME (LOSS)									0	0	0
COMPREHENSIVE INCOME (LOSS)									4.3	12.5	49.2
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									4.3	12.5	49.2
Other Non-Guarantor Subsidiaries Of Ensco [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(352.6)	11.1	890.7
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									0	0	0
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									0	0	0
Other									(0.5)	0.7	(0.5)
NET OTHER COMPREHENSIVE INCOME (LOSS)									(0.5)	0.7	(0.5)
COMPREHENSIVE INCOME (LOSS)									(353.1)	11.8	890.2
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									(3.1)	0.5	(6.9)
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									(356.2)	12.3	883.3
Consolidating Adjustments [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									407	55.1	(1,041.2)
OTHER COMPREHENSIVE INCOME (LOSS), NET
Net change in fair value of derivatives									0	0	0
Reclassification of net (gains) losses on derivative instruments from other comprehensive income (loss) into net income (loss)									0	0	0
Other									0	0	0
NET OTHER COMPREHENSIVE INCOME (LOSS)									0	0	0
COMPREHENSIVE INCOME (LOSS)									407	55.1	(1,041.2)
COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS									0	0	0
COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO ENSCO									$ 407	$ 55.1	$ (1,041.2)

Guarantee Of Registered Secur_6

Guarantee Of Registered Securities (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Guarantor Obligations [Line Items]
Cash and cash equivalents	$ 275.1	$ 445.4	$ 1,159.7	$ 121.3
Short-term Investments	329	440
Accounts receivable	344.7	345.4
Accounts receivable from affiliates	0	0
Other	360.9	381.2
Total current assets	1,309.7	1,612
PROPERTY AND EQUIPMENT, AT COST	15,517	15,332.1
Less accumulated depreciation	2,900.8	2,458.4
Property and equipment, net	12,616.2	12,873.7	10,919.3
DUE FROM AFFILIATES	0	0
INVESTMENTS IN AFFILIATES	0	0
OTHER ASSETS, NET	97.8	140.2
TOTAL ASSETS	14,023.7	14,625.9
Accounts payable and accrued liabilities	528.5	758.5
Accounts payable to affiliates	0	0
Total current liabilities	528.5	758.5
DUE TO AFFILIATES	0	0
LONG-TERM DEBT	5,010.4	4,750.7
OTHER LIABILITIES	396	386.7
ENSCO SHAREHOLDERS' EQUITY	8,091.4	8,732.1
NONCONTROLLING INTERESTS	(2.6)	(2.1)
Total equity	8,088.8	8,730
Total liabilities and shareholders' equity	14,023.7	14,625.9
Ensco Plc [Member]
Guarantor Obligations [Line Items]
Cash and cash equivalents	199.8	185.2	892.6	94
Short-term Investments	329	440
Accounts receivable	7.3	6.9
Accounts receivable from affiliates	1,861.2	351.8
Other	0.6	0
Total current assets	2,397.9	983.9
PROPERTY AND EQUIPMENT, AT COST	1.8	1.8
Less accumulated depreciation	1.8	1.8
Property and equipment, net	0	0
DUE FROM AFFILIATES	2,413.8	3,002.1
INVESTMENTS IN AFFILIATES	8,522.6	9,098.5
OTHER ASSETS, NET	8.1	12.9
TOTAL ASSETS	13,342.4	13,097.4
Accounts payable and accrued liabilities	85.3	55.4
Accounts payable to affiliates	59.7	67.3
Total current liabilities	145	122.7
DUE TO AFFILIATES	1,432	1,402.9
LONG-TERM DEBT	3,676.5	2,841.8
OTHER LIABILITIES	0.1	0
ENSCO SHAREHOLDERS' EQUITY	8,088.8	8,730
NONCONTROLLING INTERESTS	0	0
Total equity	8,088.8	8,730
Total liabilities and shareholders' equity	13,342.4	13,097.4
ENSCO International Inc. [Member]
Guarantor Obligations [Line Items]
Cash and cash equivalents	0	0	0	0
Short-term Investments	0	0
Accounts receivable	25.4	0.4
Accounts receivable from affiliates	171.4	492.7
Other	6	8.8
Total current assets	202.8	501.9
PROPERTY AND EQUIPMENT, AT COST	125.2	120.8
Less accumulated depreciation	91.3	77.1
Property and equipment, net	33.9	43.7
DUE FROM AFFILIATES	234.5	2,618
INVESTMENTS IN AFFILIATES	3,713.7	3,591.9
OTHER ASSETS, NET	0	5
TOTAL ASSETS	4,184.9	6,760.5
Accounts payable and accrued liabilities	32	39
Accounts payable to affiliates	139.5	458.3
Total current liabilities	171.5	497.3
DUE TO AFFILIATES	1,226.9	3,559.2
LONG-TERM DEBT	149.3	149.2
OTHER LIABILITIES	64.3	3.1
ENSCO SHAREHOLDERS' EQUITY	2,572.9	2,551.7
NONCONTROLLING INTERESTS	0	0
Total equity	2,572.9	2,551.7
Total liabilities and shareholders' equity	4,184.9	6,760.5
Pride International Inc. [Member]
Guarantor Obligations [Line Items]
Cash and cash equivalents	2.7	25.6	19.8	2
Short-term Investments	0	0
Accounts receivable	0	0
Accounts receivable from affiliates	0	0
Other	0	0
Total current assets	2.7	25.6
PROPERTY AND EQUIPMENT, AT COST	0	0
Less accumulated depreciation	0	0
Property and equipment, net	0	0
DUE FROM AFFILIATES	125	165.1
INVESTMENTS IN AFFILIATES	1,199.9	1,106.6
OTHER ASSETS, NET	0	0
TOTAL ASSETS	1,327.6	1,297.3
Accounts payable and accrued liabilities	12.7	21.7
Accounts payable to affiliates	38.2	12.4
Total current liabilities	50.9	34.1
DUE TO AFFILIATES	1,366.5	753.9
LONG-TERM DEBT	502.6	1,106
OTHER LIABILITIES	0	0
ENSCO SHAREHOLDERS' EQUITY	(592.4)	(596.7)
NONCONTROLLING INTERESTS	0	0
Total equity	(592.4)	(596.7)
Total liabilities and shareholders' equity	1,327.6	1,297.3
Other Non-Guarantor Subsidiaries Of Ensco [Member]
Guarantor Obligations [Line Items]
Cash and cash equivalents	72.6	234.6	247.3	25.3
Short-term Investments	0	0
Accounts receivable	312	338.1
Accounts receivable from affiliates	131.7	424.3
Other	354.3	372.4
Total current assets	870.6	1,369.4
PROPERTY AND EQUIPMENT, AT COST	15,390	15,209.5
Less accumulated depreciation	2,807.7	2,379.5
Property and equipment, net	12,582.3	12,830
DUE FROM AFFILIATES	2,715.1	3,736.1
INVESTMENTS IN AFFILIATES	0	0
OTHER ASSETS, NET	89.7	226.5
TOTAL ASSETS	16,257.7	18,162
Accounts payable and accrued liabilities	398.5	642.4
Accounts payable to affiliates	1,926.9	730.8
Total current liabilities	2,325.4	1,373.2
DUE TO AFFILIATES	1,463	3,805.3
LONG-TERM DEBT	682	653.7
OTHER LIABILITIES	331.6	487.8
ENSCO SHAREHOLDERS' EQUITY	11,458.3	11,844.1
NONCONTROLLING INTERESTS	(2.6)	(2.1)
Total equity	11,455.7	11,842
Total liabilities and shareholders' equity	16,257.7	18,162
Consolidating Adjustments [Member]
Guarantor Obligations [Line Items]
Cash and cash equivalents	0	0	$ 0	$ 0
Short-term Investments	0	0
Accounts receivable	0	0
Accounts receivable from affiliates	(2,164.3)	(1,268.8)
Other	0	0
Total current assets	(2,164.3)	(1,268.8)
PROPERTY AND EQUIPMENT, AT COST	0	0
Less accumulated depreciation	0	0
Property and equipment, net	0	0
DUE FROM AFFILIATES	(5,488.4)	(9,521.3)
INVESTMENTS IN AFFILIATES	(13,436.2)	(13,797)
OTHER ASSETS, NET	0	(104.2)
TOTAL ASSETS	(21,088.9)	(24,691.3)
Accounts payable and accrued liabilities	0	0
Accounts payable to affiliates	(2,164.3)	(1,268.8)
Total current liabilities	(2,164.3)	(1,268.8)
DUE TO AFFILIATES	(5,488.4)	(9,521.3)
LONG-TERM DEBT	0	0
OTHER LIABILITIES	0	(104.2)
ENSCO SHAREHOLDERS' EQUITY	(13,436.2)	(13,797)
NONCONTROLLING INTERESTS	0	0
Total equity	(13,436.2)	(13,797)
Total liabilities and shareholders' equity	$ (21,088.9)	$ (24,691.3)

Guarantee Of Registered Secur_7

Guarantee Of Registered Securities (Condensed Consolidating Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
NET INCOME (LOSS)	$ (203.1)	$ (142.9)	$ (150.1)	$ (140.5)	$ (207.1)	$ (28.2)	$ (44.3)	$ (24.6)	$ (636.6)	$ (304.2)	$ 897.1
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									(55.7)	259.4	1,077.4
INVESTING ACTIVITIES
Maturities of short-term investments									1,030	2,042.5	2,212
Purchases of short-term investments									(919)	(1,040)	(2,474.6)
Purchase of Affiliate Debt									0	0	0
Acquisition of Atwood, net of cash acquired									0	(871.6)	0
Sale of affiliate debt									0
Additions to property and equipment									(426.7)	(536.7)	(322.2)
Net proceeds from disposition of assets									11	2.8	9.8
Net cash used in investing activities of continuing operations									(304.7)	(403)	(575)
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									1,000	0	849.5
Advances (to) from affiliates									0	0	0
Reduction of long-term borrowings									(771.2)	(537)	(863.9)
Proceeds from equity issuance									0	0	585.5
Cash dividends paid									(17.9)	(13.8)	(11.6)
Debt financing costs									(17)	(12)	(23.4)
Other									(5.7)	(7.7)	(7.1)
Net cash provided by (used in) financing activities									188.2	(570.5)	529
Net cash provided by (used in) discontinued operations									2.5	(0.8)	8.4
Effect of exchange rate changes on cash and cash equivalents									(0.6)	0.6	(1.4)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(170.3)	(714.3)	1,038.4
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				445.4				1,159.7	445.4	1,159.7	121.3
CASH AND CASH EQUIVALENTS, END OF YEAR	275.1				445.4				275.1	445.4	1,159.7
Ensco Plc [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(639.7)	(303.7)	890.2
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									18.1	(18.2)	(101.3)
INVESTING ACTIVITIES
Maturities of short-term investments									1,030	1,748	2,062
Purchases of short-term investments									(919)	(1,022.9)	(2,047.1)
Purchase of Affiliate Debt									(551.7)	(316.3)	(237.9)
Acquisition of Atwood, net of cash acquired										0
Sale of affiliate debt									479
Additions to property and equipment									0	0	0
Net proceeds from disposition of assets										0	0
Net cash used in investing activities of continuing operations									38.3	408.8	(223)
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									1,000		0
Advances (to) from affiliates									(845)	(848.9)
Reduction of long-term borrowings									(159.9)	(220.7)	(626)
Proceeds from equity issuance											585.5
Cash dividends paid									(17.9)	(13.8)	(11.6)
Debt financing costs									(17)	(12)	(23.4)
Proceeds from Contributions from Affiliates											1,200.6
Other									(2)	(2.6)	(2.2)
Net cash provided by (used in) financing activities									(41.8)	(1,098)	1,122.9
Net cash provided by (used in) discontinued operations									0	0	0
Effect of exchange rate changes on cash and cash equivalents									0	0	0
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									14.6	(707.4)	798.6
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				185.2				892.6	185.2	892.6	94
CASH AND CASH EQUIVALENTS, END OF YEAR	199.8				185.2				199.8	185.2	892.6
ENSCO International Inc. [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(55.6)	(79.2)	108.2
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									(135.1)	(117.6)	(46.5)
INVESTING ACTIVITIES
Maturities of short-term investments									0	5.5	0
Purchases of short-term investments									0	0	(5.5)
Purchase of Affiliate Debt									0	0	0
Acquisition of Atwood, net of cash acquired										0
Sale of affiliate debt									0
Additions to property and equipment									0	0	0
Net proceeds from disposition of assets									0	0	0
Net cash used in investing activities of continuing operations									0	5.5	(5.5)
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									0		0
Reduction of long-term borrowings									0	0	0
Proceeds from equity issuance											0
Cash dividends paid									0	0	0
Debt financing costs									0	0	0
Proceeds from Contributions from Affiliates									135.1	112.1	52
Other									0	0	0
Net cash provided by (used in) financing activities									135.1	112.1	52
Net cash provided by (used in) discontinued operations									0	0	0
Effect of exchange rate changes on cash and cash equivalents									0	0	0
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									0	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				0				0	0	0	0
CASH AND CASH EQUIVALENTS, END OF YEAR	0				0				0	0	0
Pride International Inc. [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									4.3	12.5	49.2
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									(97.6)	(100.1)	(116.9)
INVESTING ACTIVITIES
Maturities of short-term investments									0	0	0
Purchases of short-term investments									0	0	0
Purchase of Affiliate Debt									0	0	0
Acquisition of Atwood, net of cash acquired										0
Sale of affiliate debt									0
Additions to property and equipment									0	0	0
Net proceeds from disposition of assets									0	0	0
Net cash used in investing activities of continuing operations									0	0	0
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									0		0
Reduction of long-term borrowings									(537.8)	0	0
Proceeds from equity issuance											0
Cash dividends paid									0	0	0
Debt financing costs									0	0	0
Proceeds from Contributions from Affiliates									612.5	105.9	134.7
Other									0	0	0
Net cash provided by (used in) financing activities									74.7	105.9	134.7
Net cash provided by (used in) discontinued operations									0	0	0
Effect of exchange rate changes on cash and cash equivalents									0	0	0
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(22.9)	5.8	17.8
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				25.6				19.8	25.6	19.8	2
CASH AND CASH EQUIVALENTS, END OF YEAR	2.7				25.6				2.7	25.6	19.8
Other Non-Guarantor Subsidiaries Of Ensco [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									(352.6)	11.1	890.7
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									158.9	495.3	1,342.1
INVESTING ACTIVITIES
Maturities of short-term investments									0	289	150
Purchases of short-term investments									0	(17.1)	(422)
Purchase of Affiliate Debt									0	0	0
Acquisition of Atwood, net of cash acquired										(871.6)
Sale of affiliate debt									0
Additions to property and equipment									(426.7)	(536.7)	(322.2)
Net proceeds from disposition of assets									11	2.8	9.8
Net cash used in investing activities of continuing operations									(415.7)	(1,133.6)	(584.4)
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									0		849.5
Advances (to) from affiliates											(1,387.3)
Reduction of long-term borrowings									(0.8)	0	0
Proceeds from equity issuance											0
Cash dividends paid									0	0	0
Debt financing costs									0	0	0
Proceeds from Contributions from Affiliates									97.4	630.9
Other									(3.7)	(5.1)	(4.9)
Net cash provided by (used in) financing activities									92.9	625.8	(542.7)
Net cash provided by (used in) discontinued operations									2.5	(0.8)	8.4
Effect of exchange rate changes on cash and cash equivalents									(0.6)	0.6	(1.4)
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									(162)	(12.7)	222
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				234.6				247.3	234.6	247.3	25.3
CASH AND CASH EQUIVALENTS, END OF YEAR	72.6				234.6				72.6	234.6	247.3
Consolidating Adjustments [Member]
Guarantor Obligations [Line Items]
NET INCOME (LOSS)									407	55.1	(1,041.2)
OPERATING ACTIVITIES
Net cash provided by operating activities of continuing operations									0	0	0
INVESTING ACTIVITIES
Maturities of short-term investments									0	0	0
Purchases of short-term investments									0	0	0
Purchase of Affiliate Debt									551.7	316.3	237.9
Acquisition of Atwood, net of cash acquired										0
Sale of affiliate debt									(479)
Additions to property and equipment									0	0	0
Net proceeds from disposition of assets									0	0	0
Net cash used in investing activities of continuing operations									72.7	316.3	237.9
FINANCING ACTIVITIES
Proceeds from issuance of senior notes									0		0
Advances (to) from affiliates									0	0	0
Reduction of long-term borrowings									(72.7)	(316.3)	(237.9)
Proceeds from equity issuance											0
Cash dividends paid									0	0	0
Debt financing costs									0	0	0
Other									0	0	0
Net cash provided by (used in) financing activities									(72.7)	(316.3)	(237.9)
Net cash provided by (used in) discontinued operations									0	0	0
Effect of exchange rate changes on cash and cash equivalents									0	0	0
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS									0	0	0
CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR				$ 0				$ 0	0	0	0
CASH AND CASH EQUIVALENTS, END OF YEAR	$ 0				$ 0				$ 0	$ 0	$ 0

Unaudited Quarterly Financial_3

Unaudited Quarterly Financial Data (Summary Of Unaudited Quarterly Consolidated Income Statement) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended									9 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Revenues	$ 399	$ 430.9	$ 458.5	$ 417	$ 454.2	$ 460.2	$ 457.5	$ 471.1			$ 1,705.4	$ 1,843	$ 2,776.4
Contract drilling (exclusive of depreciation)	322.8	327.1	344.3	325.2	334.3	285.8	291.3	278.1			1,319.4	1,189.5	1,301
Loss on impairment	40.3	0	0	0	182.9	0	0	0			40.3	182.9	0
Depreciation expense	122.4	120.6	120.7	115.2	119.5	108.2	107.9	109.2			478.9	444.8	445.3
General and administrative	23.6	25.1	26.1	27.9	70.9	30.4	30.5	26			102.7	157.8	100.8
OPERATING INCOME (LOSS)	(110.1)	(41.9)	(32.6)	(51.3)	(253.4)	35.8	27.8	57.8			(235.9)	(132)	929.3
Other expense, net	(69.8)	(77.7)	(84.8)	(70.7)	87.3	(40.4)	(53.2)	(57.7)			(303)	(64)	68.2
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	(179.9)	(119.6)	(117.4)	(122)	(166.1)	(4.6)	(25.4)	0.1			(538.9)	(196)	997.5
Provision for income taxes	23.2	23.3	24.7	18.4	42.4	23.4	19.3	24.1			89.6	109.2	108.5
INCOME (LOSS) FROM CONTINUING OPERATIONS	(203.1)	(142.9)	(142.1)	(140.4)	(208.5)	(28)	(44.7)	(24)			(628.5)	(305.2)	889
INCOME (LOSS) FROM DISCONTINUED OPERATIONS, NET	0	0	(8)	(0.1)	1.4	(0.2)	0.4	(0.6)	$ 8.1		(8.1)	1	8.1
NET INCOME (LOSS)	(203.1)	(142.9)	(150.1)	(140.5)	(207.1)	(28.2)	(44.3)	(24.6)			(636.6)	(304.2)	897.1
NET (INCOME) LOSS ATTRIBUTABLE TO NONCONTROLLING INTERESTS	(0.5)	(2.1)	(0.9)	0.4	0	2.8	(1.2)	(1.1)			(3.1)	0.5	(6.9)
NET INCOME (LOSS) ATTRIBUTABLE TO ENSCO	$ (203.6)	$ (145)	$ (151)	$ (140.1)	$ (207.1)	$ (25.4)	$ (45.5)	$ (25.7)			$ (639.7)	$ (303.7)	$ 890.2
Loss per share – basic and diluted
Continuing operations	$ (0.47)	$ (0.33)	$ (0.33)	$ (0.32)	$ (0.49)	$ (0.08)	$ (0.15)	$ (0.09)			$ (1.45)	$ (0.91)	$ 3.10
Discontinued operations	0	0	(0.02)	0	0	0	0	0			(0.02)	0	0.03
Total earnings per share - basic	$ (0.47)	$ (0.33)	$ (0.35)	$ (0.32)	$ (0.49)	$ (0.08)	$ (0.15)	$ (0.09)			$ (1.47)	$ (0.91)	$ 3.13
Business Combination, Integration Related Costs, Contract Dilling Expense	$ 7
Business Combination, Integration Related Costs, G&A	30.9
Merger related costs	$ 11.5
Bargain purchase gain										$ 142	$ 1.8	$ 140.2	$ 0
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense (Benefit)												16.5
Gain (Loss) on Extinguishment of Debt								$ 6.2			$ (19)	$ (2.6)	$ 287.8
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Provisional Income Tax Expense (Benefit)					$ 16.5