Kosmos Energy (KOS) 10-Q5 May 142014 Q1 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
Document and Entity Information	Mar. 31, 2014	Apr. 28, 2014
Document and Entity Information	'	'
Entity Registrant Name	'Kosmos Energy Ltd.	'
Entity Central Index Key	'0001509991	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	387,593,151
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:	'	'
Cash and cash equivalents	$528,028	$598,108
Restricted cash	20,135	21,475
Receivables:	'	'
Joint interest billings	102,843	19,930
Oil sales	'	281
Other	5,783	1,115
Inventories	42,490	47,424
Prepaid expenses and other	37,494	27,010
Current deferred tax assets	22,806	19,618
Derivatives	510	'
Total current assets	760,089	734,961
Property and equipment:	'	'
Oil and gas properties, net	1,530,666	1,508,062
Other property, net	14,155	14,900
Property and equipment, net	1,544,821	1,522,962
Other assets:	'	'
Restricted cash	35,250	31,500
Deferred financing costs, net of accumulated amortization of $25,626 and $24,976 at March 31, 2014 and December 31, 2013, respectively	55,216	40,111
Long-term deferred tax assets	17,985	16,292
Total assets	2,413,361	2,345,826
Current liabilities:	'	'
Accounts payable	103,563	94,172
Accrued liabilities	150,524	115,212
Derivatives	8,107	9,940
Total current liabilities	262,194	219,324
Long-term liabilities:	'	'
Long-term debt	800,000	900,000
Derivatives	4,195	3,811
Asset retirement obligations	40,643	39,596
Deferred tax liability	205,509	170,226
Other long-term liabilities	16,093	20,534
Total long-term liabilities	1,066,440	1,134,167
Shareholders' equity:	'	'
Preference shares, $0.01 par value; 200,000,000 authorized shares; zero issued at March 31, 2014 and December 31, 2013	'	'
Common shares, $0.01 par value; 2,000,000,000 authorized shares; 392,025,211 and 391,974,287 issued at March 31, 2014 and December 31, 2013, respectively	3,920	3,920
Additional paid-in capital	1,799,435	1,781,535
Accumulated deficit	-699,251	-774,220
Accumulated other comprehensive income	1,752	2,158
Treasury stock, at cost, 4,426,769 and 4,400,135 shares at March 31, 2014 and December 31, 2013, respectively	-21,129	-21,058
Total shareholders' equity	1,084,727	992,335
Total liabilities and shareholders' equity	$2,413,361	$2,345,826

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
CONSOLIDATED BALANCE SHEETS	'	'
Deferred financing costs, accumulated amortization (in dollars)	$25,626	$24,976
Preference shares, par value (in dollars per share)	$0.01	$0.01
Preference shares, authorized shares	200,000,000	200,000,000
Preference shares, issued shares	0	0
Common shares, par value (in dollars per share)	$0.01	$0.01
Common shares, authorized shares	2,000,000,000	2,000,000,000
Common shares, issued shares	392,025,211	391,974,287
Treasury stock, shares	4,426,769	4,400,135

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues and other income:	'	'
Oil and gas revenue	$212,853	$228,066
Gain on sale of assets	23,769	'
Interest income	58	70
Other income	439	254
Total revenues and other income	237,119	228,390
Costs and expenses:	'	'
Oil and gas production	16,323	24,401
Exploration expenses	12,809	24,255
General and administrative	27,413	39,071
Depletion and depreciation	46,378	58,649
Amortization-deferred financing costs	2,786	2,698
Interest expense	3,511	8,991
Derivatives, net	-2,028	5,508
Loss on extinguishment of debt	2,898	'
Other expenses, net	1,277	632
Total costs and expenses	111,367	164,205
Income before income taxes	125,752	64,185
Income tax expense	50,783	44,091
Net income	$74,969	$20,094
Net income per share	'	'
Basic (in dollars per share)	$0.20	$0.05
Diluted (in dollars per share)	$0.19	$0.05
Weighted average number of shares used to compute net income per share:	'	'
Basic (in shares)	377,830	375,284
Diluted (in shares)	381,472	375,651

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME	'	'
Net income	$74,969	$20,094
Other comprehensive loss:	'	'
Reclassification adjustments for derivative gains included in net income	-406	-359
Other comprehensive loss	-406	-359
Comprehensive income	$74,563	$19,735

CONSOLIDATED_STATEMENTS_OF_SHA

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $)	Total	Common Shares	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Treasury Stock
In Thousands, unless otherwise specified	Total	Common Shares	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Treasury Stock
Balance at Dec. 31, 2013	$992,335	$3,920	$1,781,535	($774,220)	$2,158	($21,058)
Balance (in shares) at Dec. 31, 2013	'	391,974	'	'	'	'
Increase (Decrease) in Shareholders' Equity	'	'	'	'	'	'
Equity-based compensation	17,900	'	17,900	'	'	'
Derivatives, net	-406	'	'	'	-406	'
Restricted stock awards and units (in shares)	'	51	'	'	'	'
Purchase of treasury stock	-71	'	'	'	'	-71
Net income	74,969	'	'	74,969	'	'
Balance at Mar. 31, 2014	$1,084,727	$3,920	$1,799,435	($699,251)	$1,752	($21,129)
Balance (in shares) at Mar. 31, 2014	'	392,025	'	'	'	'

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities	'	'
Net income	$74,969	$20,094
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depletion, depreciation and amortization	49,164	61,347
Deferred income taxes	30,267	20,915
Unsuccessful well costs	-245	9,753
Change in fair value of derivatives	-810	534
Cash settlements on derivatives	-1,555	-4,850
Equity-based compensation	17,900	18,938
Gain on sale of assets	-23,769	'
Loss on extinguishment of debt	2,898	'
Other	-4,220	1,396
Changes in assets and liabilities:	'	'
Increase in receivables	-63,566	-2,382
Decrease in inventories	4,872	3,637
Increase in prepaid expenses and other	-10,484	-298
Increase (decrease) in accounts payable	9,391	-80,070
Increase in accrued liabilities	28,774	17,855
Net cash provided by operating activities	113,586	66,869
Investing activities	'	'
Oil and gas assets	-96,486	-83,491
Other property	-428	-814
Proceeds on sale of assets	34,581	'
Restricted cash	-2,410	886
Net cash used in investing activities	-64,743	-83,419
Financing activities	'	'
Payments on long-term debt	-100,000	'
Purchase of treasury stock	-71	-82
Deferred financing costs	-18,852	-1,243
Net cash used in financing activities	-118,923	-1,325
Net decrease in cash and cash equivalents	-70,080	-17,875
Cash and cash equivalents at beginning of period	598,108	515,164
Cash and cash equivalents at end of period	528,028	497,289
Cash paid for:	'	'
Interest	7,280	6,585
Income taxes	$20,431	$4,300

Organization

Organization	3 Months Ended
Organization	Mar. 31, 2014
Organization	'
Organization	'
	1. Organization

	Kosmos Energy Ltd. was incorporated pursuant to the laws of Bermuda in January 2011 to become a holding company for Kosmos Energy Holdings. Kosmos Energy Holdings is a privately held Cayman Islands company that was formed in March 2004. As a holding company, Kosmos Energy Ltd.’s management operations are conducted through a wholly owned subsidiary, Kosmos Energy, LLC. The terms “Kosmos,” the “Company,” “we,” “us,” “our,” “ours,” and similar terms refer to Kosmos Energy Ltd. and its wholly owned subsidiaries, unless the context indicates otherwise.

	We are a leading independent oil and gas exploration and production company focused on frontier and emerging areas along the Atlantic Margin. Our assets include existing production and other major development projects offshore Ghana, as well as exploration licenses with significant hydrocarbon potential offshore Ireland, Mauritania, Morocco (including Western Sahara) and Suriname. Kosmos is listed on the New York Stock Exchange and is traded under the ticker symbol KOS.

	We have one reportable segment, which is the exploration and production of oil and natural gas. Substantially all of our long-lived assets and product sales are currently related to production located offshore Ghana.

Accounting_Policies

Accounting Policies	3 Months Ended
Accounting Policies	Mar. 31, 2014
Accounting Policies	'
Accounting Policies	'
	2. Accounting Policies

	General

	The interim-period financial information presented in the consolidated financial statements included in this report is unaudited and, in the opinion of management, includes all adjustments of a normal recurring nature necessary to present fairly the consolidated financial position as of March 31, 2014, the changes in the consolidated statements of shareholders’ equity for the three months ended March 31, 2014, the consolidated results of operations for the three months ended March 31, 2014 and 2013, and consolidated cash flows for the three months ended March 31, 2014 and 2013. The results of the interim periods shown in this report are not necessarily indicative of the final results to be expected for the full year. The consolidated financial statements were prepared in accordance with the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain notes or other financial information that are normally required by Generally Accepted Accounting Principles (“GAAP”) have been condensed or omitted from these interim consolidated financial statements. These consolidated financial statements and the accompanying notes should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2013, included in our annual report on Form 10-K.

	Reclassifications

	Certain prior period amounts have been reclassified to conform with the current year presentation. Such reclassifications had no impact on our reported net loss, current assets, total assets, current liabilities, total liabilities or shareholders’ equity.

	Restricted Cash

	In accordance with our commercial debt facility, we are required to maintain a restricted cash balance that is sufficient to meet the payment of interest and fees for the next six-month period. As of March 31, 2014 and December 31, 2013, we had $19.1 million and $18.6 million, respectively, in current restricted cash to meet this requirement. In addition, in accordance with certain of our petroleum contracts, we have posted letters of credit related to performance guarantees for our minimum work obligations. These letters of credit are cash collateralized in accounts held by us and as such are classified as restricted cash. Upon completion of the minimum work obligations and/or entering into the next phase of the petroleum contract, the requirement to post the existing letters of credit will be satisfied and the cash collateral will be released. However, additional letters of credit may be required should we choose to move into the next phase of certain of our petroleum contracts. As of March 31, 2014 and December 31, 2013, we had $1.0 million and $2.9 million, respectively, of current restricted cash and $35.3 million and $31.5 million, respectively, of long-term restricted cash used to cash collateralize performance guarantees related to our petroleum contracts.

	Inventories

	Inventories consisted of $37.5 million and $45.8 million of materials and supplies and $5.0 million and $1.6 million of hydrocarbons as of March 31, 2014 and December 31, 2013, respectively. The Company’s materials and supplies inventory primarily consists of casing and wellheads and is stated at the lower of cost, using the weighted average cost method, or market.

	Hydrocarbon inventory is carried at the lower of cost, using the weighted average cost method, or market. Hydrocarbon inventory costs include expenditures and other charges incurred in bringing the inventory to its existing condition. Selling expenses and general and administrative expenses are reported as period costs and excluded from inventory costs.

	Variable Interest Entity

	Our wholly owned subsidiary, Kosmos Energy Finance International, is a variable interest entity (“VIE”). The Company is the primary beneficiary of this VIE, which is consolidated in these financial statements.

	Kosmos Energy Finance International’s following assets and liabilities are shown separately on the face of the consolidated balance sheets as of March 31, 2014 and December 31, 2013: current derivatives asset; long-term debt and current and long-term derivatives liabilities. At March 31, 2014, Kosmos Energy Finance International had $18.6 million in cash and cash equivalents; $19.1 million in current restricted cash; $50.0 million deferred financing costs, net; $2.0 million in accrued liabilities and $4.1 million in other long-term liabilities, which are included in the amounts shown on the face of the consolidated balance sheets. At December 31, 2013, Kosmos Energy Finance International had $38.1 million in cash and cash equivalents; $18.6 million in current restricted cash; $0.2 million in prepaid expenses and other; $34.2 million deferred financing costs, net; $1.4 million in accrued liabilities and $8.2 million in other long-term liabilities, which are included in the amounts shown on the face of the consolidated balance sheets.

Property_and_Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2014
Property and Equipment	'
Property and Equipment	'
	3. Property and Equipment

	Property and equipment is stated at cost and consisted of the following:

		March 31,			December 31,
		2014			2013
		(In thousands)
	Oil and gas properties:
	Proved properties	$	832,569		$	801,348
	Unproved properties	555,145			524,257
	Support equipment and facilities	714,803			710,289
	Total oil and gas properties	2,102,517			2,035,894
	Less: accumulated depletion	(571,851		)	(527,832		)
	Oil and gas properties, net	1,530,666			1,508,062

	Other property	32,225			31,658
	Less: accumulated depreciation	(18,070		)	(16,758		)
	Other property, net	14,155			14,900

	Property and equipment, net	$	1,544,821		$	1,522,962

	We recorded depletion expense of $44.0 million and $56.6 million for the three months ended March 31, 2014 and 2013, respectively.

	In the first quarter of 2014, the Moroccan government issued a joint ministerial order approving a partial sale of our participating interests to BP plc (“BP”) covering our three blocks in the Agadir Basin, offshore Morocco. Upon receipt of this order, we closed the transactions with BP. Certain governmental administrative processes required to officially reflect the transactions under Moroccan law are expected to be completed in due course. Under the terms of the agreements, BP acquired a non-operating interest in each of the Essaouira Offshore, Foum Assaka Offshore and Tarhazoute Offshore blocks. The sales price of the farm-outs was $56.9 million. As of March 31, 2014, we received $34.6 million, with the remaining $22.3 million recorded as a joint interest billings receivable. After giving effect to these farm-outs, our participating interests will be 30.0%, 29.925% and 30.0% in the Essaouira Offshore, Foum Assaka Offshore and Tarhazoute Offshore blocks, respectively, and we will remain the operator. As part of the transaction, the proceeds on the sale of the interests exceeded our book basis in the assets, resulting in a $23.8 million gain on the transaction.

	In the first quarter of 2014, the Moroccan government issued a joint ministerial order approving a partial sale of our participating interest to Capricorn Exploration and Development Company Limited, a wholly owned subsidiary of Cairn Energy PLC (“Cairn”), covering the Cap Boujdour Offshore block, offshore Western Sahara. Upon receipt of this order, we closed the transaction with Cairn. Certain governmental administrative processes required to officially reflect the transaction under Moroccan law are expected to be completed in due course. Cairn will pay $1.5 million for their share of costs incurred from the effective date of the farm-out agreement through the closing date. After giving effect to the farm-out, our participating interest in the Cap Boujdour Offshore block will be 55.0% and we will remain the operator.

Suspended_Well_Costs

Suspended Well Costs	3 Months Ended
	Mar. 31, 2014
Suspended Well Costs	'
Suspended Well Costs	'
	4. Suspended Well Costs

	The following table provides an aging of capitalized exploratory well costs based on the date drilling was completed and the number of projects for which exploratory well costs have been capitalized for more than one year since the completion of drilling:

		March 31, 2014		December 31, 2013
		(In thousands, except well counts)
	Exploratory well costs capitalized for a period of one year or less	$	11,456	$	11,426
	Exploratory well costs capitalized for a period one to two years	175,162		229,140
	Exploratory well costs capitalized for a period three to five years	189,335		135,600
	Ending balance	$	375,953	$	376,166
	Number of projects that have exploratory well costs that have been capitalized for a period greater than one year	8		8

	As of March 31, 2014, the projects with exploratory well costs capitalized for more than one year since the completion of drilling are related to the Mahogany, Teak-1, Teak-2 and Akasa discoveries in the West Cape Three Points (“WCTP”) Block and the Tweneboa, Enyenra, Ntomme and Wawa discoveries in the Deepwater Tano (“DT”) Block, which are all in Ghana.

	Effective January 14, 2014, the Ministry of Energy and Ghana National Petroleum Corporation (“GNPC”) entered into a Memorandum of Understanding with Kosmos Energy, on behalf of the WCTP Petroleum Agreement (“PA”) Block partners, wherein all parties have settled all matters pertaining to the Notices of Dispute for the Mahogany East PoD, and the Ministry of Energy has approved the Appraisal Programs for the Mahogany, Teak, and Akasa discoveries.

	Mahogany— Three appraisal wells have been drilled. Additionally, we deepened a development well in the Jubilee Field to further appraise the Mahogany discovery. Following additional appraisal and evaluation, a decision regarding commerciality of the Mahogany discovery is expected to be made by the WCTP Block partners in 2015. Within six months of such a declaration, a PoD would be prepared and submitted to Ghana’s Ministry of Energy, as required under the WCTP PA.

	Teak-1 Discovery—Two appraisal wells have been drilled. Following additional appraisal and evaluation, a decision regarding commerciality of the Teak-1 discovery is expected to be made by the WCTP Block partners in 2015. Within six months of such a declaration, a PoD would be prepared and submitted to Ghana’s Ministry of Energy, as required under the WCTP PA.

	Teak-2 Discovery—We have performed a gauge installation on the well and are reprocessing seismic data. Following additional appraisal and evaluation, a decision regarding commerciality of the Teak-2 discovery is expected to be made by the WCTP Block partners in 2015. Within six months of such a declaration, a PoD would be prepared and submitted to Ghana’s Ministry of Energy, as required under the WCTP PA.

	Akasa Discovery—We performed a drill stem test and gauge installation on the discovery well and drilled one appraisal well, the Akasa-2A. Following additional appraisal and evaluation, a decision regarding commerciality of the Akasa discovery is expected to be made by the WCTP Block partners in 2015. Within six months of such a declaration, a PoD would be prepared and submitted to Ghana’s Ministry of Energy, as required under the WCTP PA.

	Tweneboa, Enyenra and Ntomme (“TEN”) Discoveries—In May 2013, the government of Ghana approved the PoD over the TEN discoveries. Development of TEN will include the drilling and completion of up to 24 development wells, half of the wells are designed as producers, with the remaining wells designed for water or gas injection. The TEN project is expected to deliver first oil in the second half of 2016. The costs associated with the TEN development will remain as unproved property pending the determination of whether the discoveries are associated with proved reserves.

	Wawa Discovery—We are currently reprocessing seismic data and acquiring a high resolution seismic survey over the discovery area. Following additional evaluation and potential appraisal activities, a decision regarding commerciality of the Wawa discovery is expected to be made by the DT Block partners in 2015. Within six months of such declaration, a PoD would be prepared and submitted to Ghana’s Ministry of Energy, as required under the DT PA.

Accrued_Liabilities

Accrued Liabilities	3 Months Ended
	Mar. 31, 2014
Accrued Liabilities	'
Accrued Liabilities	'
	5. Accrued Liabilities

	Accrued liabilities consisted of the following:

		March 31,		December 31,
		2014		2013
		(In thousands)
	Accrued liabilities:
	Accrued exploration, development and production	$	101,360	$	73,976
	Income taxes	20,463		20,379
	Accrued taxes other than income	16,560		15,188
	Accrued general and administrative expenses	9,462		4,255
	Accrued other	2,679		1,414
		$	150,524	$	115,212

Debt

3 Months Ended

Mar. 31, 2014

Debt

6. Debt

Facility

In March 2014, the Company amended and restated the then existing commercial debt facility (the “Facility”) with a total commitment of $1.5 billion from a number of financial institutions. The Facility supports our oil and gas exploration, appraisal and development programs and corporate activities.

As part of the debt refinancing in March 2014, the repayment of borrowings under the existing facility attributable to financial institutions that did not participate in the amended Facility was accounted for as an extinguishment of debt, and existing unamortized debt issuance costs attributable to those participants were expensed. As a result, we recorded a $2.9 million loss on the extinguishment of debt. As of March 31, 2014, we have $50.0 million of net deferred financing costs related to the Facility, which will be amortized over the remaining term of the Facility, including certain costs related to the amendment.

As of March 31, 2014, borrowings under the Facility totaled $800.0 million and the undrawn availability under the Facility was $700.0 million.

Interest is the aggregate of the applicable margin (3.25% to 4.50%, depending on the length of time that has passed from the date the Facility was entered into); LIBOR; and mandatory cost (if any, as defined in the Facility). Interest is payable on the last day of each interest period (and, if the interest period is longer than six months, on the dates falling at six-month intervals after the first day of the interest period). We pay commitment fees on the undrawn and unavailable portion of the total commitments, if any. Commitment fees are equal to 40% per annum of the then-applicable respective margin when a commitment is available for utilization and, equal to 20% per annum of the then-applicable respective margin when a commitment is not available for utilization. We recognize interest expense in accordance with ASC 835—Interest, which requires interest expense to be recognized using the effective interest method. As part of the March 2014 amendment, the Facility’s estimated effective interest rate was changed and, accordingly, we adjusted our estimate of deferred interest previously recorded during prior years by $4.5 million, which was recorded as a reduction to interest expense.

The Facility provides a revolving-credit and letter of credit facility. The availability period for the revolving-credit facility, as amended in March 2014 expires on March 31, 2018, however the Facility has a revolving-credit sublimit, which will be the lesser of $500.0 million and the total available facility at that time, that will be available for drawing until the date falling one month prior to the final maturity date. The letter of credit sublimit expires on the final maturity date. The available facility amount is subject to borrowing base constraints and, beginning on March 31, 2018, outstanding borrowings will be constrained by an amortization schedule. The Facility has a final maturity date of March 31, 2021. As of March 31, 2014, we had no letters of credit issued under the Facility.

Kosmos has the right to cancel all the undrawn commitments under the Facility. The amount of funds available to be borrowed under the Facility, also known as the borrowing base amount, is determined each year on March 31 and September 30 as part of a forecast that is prepared by and agreed to by us and the Technical and Modeling Bank and the Facility Agent. The formula to calculate the borrowing base amount is based on the sum of the net present values of net cash flows and relevant capital expenditures reduced by certain percentages as well as value attributable to certain assets’ reserves and/or resources.

If an event of default exists under the Facility, the lenders can accelerate the maturity and exercise other rights and remedies, including the enforcement of security granted pursuant to the Facility over certain assets held by us. The Facility contains cross default provisions related to the Corporate Revolver and Revolving Letter of Credit Facility (“LC Facility”).

We were in compliance with the financial covenants contained in the Facility as of the March 31, 2014 (the most recent assessment date).

Corporate Revolver

In November 2012, we secured a Corporate Revolver from a number of financial institutions. In April 2013, the availability under the Corporate Revolver was increased from $260.0 million to $300.0 million due to additional commitments received from existing and new financial institutions. As of March 31, 2014, there were no borrowings outstanding under the Corporate Revolver and the undrawn availability under the Corporate Revolver was $300.0 million. The Corporate Revolver contains cross default provisions related to the Facility and the LC Facility.

Revolving Letter of Credit Facility

In July 2013, we entered into a LC Facility. The size of the LC Facility is $100.0 million, with additional commitments up to $50.0 million being available if the existing lender increases its commitment or if commitments from new financial institutions are added. As of March 31, 2014, we had $35.3 million of restricted cash collateralizing seven outstanding letters of credit under the LC Facility. The LC Facility contains cross default provisions related to the Facility and the Corporate Revolver.

At March 31, 2014, the estimated repayments of debt during the five fiscal year periods and thereafter are as follows:

Payments Due by Year

2014(1)

2015

2016

2017

2018

Thereafter

(In thousands)

Facility(2)

—

35,812

764,188

(1) Represents payments for the period April 1, 2014 through December 31, 2014.

(2) The scheduled maturities of debt are based on the level of borrowings and the estimated future available borrowing base as of March 31, 2014. Any increases or decreases in the level of borrowings or decreases in the available borrowing base would impact the scheduled maturities of debt during the next five years and thereafter.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
Derivative Financial Instruments	Mar. 31, 2014
Derivative Financial Instruments	'
Derivative Financial Instruments	'
	7. Derivative Financial Instruments

	We use financial derivative contracts to manage exposures to commodity price and interest rate fluctuations. We do not hold or issue derivative financial instruments for trading purposes. We manage market and counterparty credit risk in accordance with our policies and guidelines. In accordance with these policies and guidelines, our management determines the appropriate timing and extent of derivative transactions.

	Oil Derivative Contracts

	The following table sets forth the volumes in barrels underlying the Company’s outstanding oil derivative contracts and the weighted average Dated Brent prices per Bbl for those contracts as of March 31, 2014.

							Weighted Average Dated Brent Price per Bbl
	Term(1)		Type of Contract		MBbl		Deferred			Swap		Floor		Ceiling		Call
							Premium
							Receivable/
							(Payable)
	2014:00:00
	April - December		Three-way collars		1,125		$	(1.22	)	$	—	$	85	$	115	$	140
	April - December		Three-way collars		753		—			—		85		115.01		140
	April - December		Three-way collars		752		—			—		88.1		110		125
	April - December		Three-way collars		1,129		1.15			—		90		113		135
	April - December		Three-way collars		752		—			—		95		115.47		130
	2015:00:00
	January - December		Three-way collars		1,730		$	(0.43	)	$	—	$	85	$	110	$	135
	January - December		Three-way collars		1,500		(0.80		)	—		90		110		135
	January - December		Swaps with calls		2,000		—			99		—		—		115


	(1) In April 2014, we entered into put contracts for 1.0 MMBbl from January 2016 through December 2016 with a floor price of $85.00 per Bbl. The put contracts are indexed to Dated Brent prices and have a weighted average deferred premium payable of $3.82 per Bbl.

	Interest Rate Swap Derivative Contracts

	The following table summarizes our open interest rate swaps as of March 31, 2014, whereby we pay a fixed rate of interest and the counterparty pays a variable LIBOR-based rate:

	Term		Weighted Average			Weighted Average		Floating Rate
	Term		Notional Amount			Fixed Rate		Floating Rate
			(In thousands)
	April 2014 — December 2014		$	133,434		1.99	%	6-month LIBOR
	January 2015 — December 2015		45,319			2.03	%	6-month LIBOR
	January 2016 — June 2016		12,500			2.27	%	6-month LIBOR


	The following tables disclose the Company’s derivative instruments as of March 31, 2014 and December 31, 2013 and gain/(loss) from derivatives during the three months ended March 31, 2014 and 2013, respectively:

					Estimated Fair Value
					Asset (Liability)
					March 31,			December 31,
	Type of Contract		Balance Sheet Location		2014			2013
					(In thousands)
	Derivatives not designated as hedging instruments:
	Derivative assets:
	Commodity		Derivatives assets—current		$	510		$	—

	Derivative liabilities:
	Commodity(1)		Derivatives liabilities—current		(5,738		)	(7,873		)
	Interest rate		Derivatives liabilities—current		(2,369		)	(2,067		)
	Commodity(2)		Derivatives liabilities—long-term		(3,732		)	(3,144		)
	Interest rate		Derivatives liabilities—long-term		(463		)	(667		)
	Total derivatives not designated as hedging instruments				$	(11,792	)	$	(13,751	)


	(1) Includes deferred premiums payable of $0.4 million and $0.1 million related to commodity derivative contracts as of March 31, 2014 and December 31, 2013, respectively.

	(2) Includes deferred premiums payable of $1.6 million and $6.5 million related to commodity derivative contracts as of March 31, 2014 and December 31, 2013, respectively.

					Amount of Gain/(Loss)
				Three Months Ended
				March 31,
Type of Contract		Location of Gain/(Loss)		2014			2013
				(In thousands)
Derivatives in cash flow hedging relationships:
Interest rate(1)		Interest expense		$	406		$	359
Total derivatives in cash flow hedging relationships				$	406		$	359

Derivatives not designated as hedging instruments:
Commodity(2)		Oil and gas revenue		$	(1,526	)	$	4,588
Commodity		Derivatives, net		2,028			(5,508		)
Interest rate		Interest expense		(98		)	27
Total derivatives not designated as hedging instruments				$	404		$	(893	)


(1) Amounts were reclassified from accumulated other comprehensive income or loss (“AOCI”) into earnings upon settlement.

(2) Amounts represent the mark-to-market portion of our provisional oil sales contracts.

Offsetting of Derivative Assets and Derivative Liabilities

Our derivative instruments subject to master netting arrangements with our counterparties only have the right of offset when there is an event of default. As of March 31, 2014 and December 31, 2013, there was not an event of default and, therefore, the associated gross asset or gross liability amounts related to these arrangements are presented on the consolidated balance sheets. Additionally, if an event of default occurred the offsetting amounts would be immaterial as of March 31, 2014 and December 31, 2013.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Fair Value Measurements	'
	8. Fair Value Measurements

	In accordance with ASC 820—Fair Value Measurements and Disclosures, fair value measurements are based upon inputs that market participants use in pricing an asset or liability, which are classified into two categories: observable inputs and unobservable inputs. Observable inputs represent market data obtained from independent sources, whereas unobservable inputs reflect a company’s own market assumptions, which are used if observable inputs are not reasonably available without undue cost and effort. We prioritize the inputs used in measuring fair value into the following fair value hierarchy:

	· Level 1—quoted prices for identical assets or liabilities in active markets.

	· Level 2—quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability and inputs derived principally from or corroborated by observable market data by correlation or other means.

	· Level 3—unobservable inputs for the asset or liability. The fair value input hierarchy level to which an asset or liability measurement in its entirety falls is determined based on the lowest level input that is significant to the measurement in its entirety.

	The following tables present the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2014 and December 31, 2013, for each fair value hierarchy level:

		Fair Value Measurements Using:
		Quoted Prices in		Significant Other			Significant
		Active Markets for		Observable Inputs			Unobservable Inputs
		Identical Assets
		(Level 1)		(Level 2)			(Level 3)		Total
		(In thousands)
	March 31, 2014
	Assets:
	Commodity derivatives	$	—	$	510		$	—	$	510
	Liabilities:
	Commodity derivatives	—		(9,470		)	—		(9,470		)
	Interest rate derivatives	—		(2,832		)	—		(2,832		)
	Total	$	—	$	(11,792	)	$	—	$	(11,792	)

	December 31, 2013
	Liabilities:
	Commodity derivatives	$	—	$	(11,017	)	$	—	$	(11,017	)
	Interest rate derivatives	—		(2,734		)	—		(2,734		)
	Total	$	—	$	(13,751	)	$	—	$	(13,751	)

	The book values of cash and cash equivalents and restricted cash approximate fair value based on Level 1 inputs. Joint interest billings, oil sales and other receivables, and accounts payable and accrued liabilities approximate fair value due to the short-term nature of these instruments. The carrying values of our debt approximates fair value since they are subject to short-term floating interest rates that approximate the rates available to us for those periods. Our long-term receivables, if any, after any allowances for doubtful accounts approximate fair value. The estimates of fair value of these items are based on Level 2 inputs.

	Commodity Derivatives

	Our commodity derivatives represent crude oil three-way collars, purchased puts and swaps with calls for notional barrels of oil at fixed Dated Brent oil prices. The values attributable to the our oil derivatives are based on (i) the contracted notional volumes, (ii) independent active futures price quotes for Dated Brent, (iii) a credit-adjusted yield curve applicable to each counterparty by reference to the CDS market and (iv) an independently sourced estimate of volatility for Dated Brent. The volatility estimate was provided by certain independent brokers who are active in buying and selling oil options and was corroborated by market-quoted volatility factors. The deferred premium is included in the fair market value of the commodity derivatives. See Note 7—Derivative Financial Instruments for additional information regarding the Company’s derivative instruments.

	Provisional Oil Sales

	The value attributable to the provisional oil sales derivative is based on (i) the sales volumes subject to provisional pricing and (ii) an independently sourced forward curve over the term of the provisional pricing period.

	Interest Rate Derivatives

	We have interest rate swaps, whereby the Company pays a fixed rate of interest and the counterparty pays a variable LIBOR-based rate. The values attributable to the Company’s interest rate derivative contracts are based on (i) the contracted notional amounts, (ii) LIBOR yield curves provided by independent third parties and corroborated with forward active market-quoted LIBOR yield curves and (iii) a credit-adjusted yield curve as applicable to each counterparty by reference to the CDS market.

Equitybased_Compensation

Equity-based Compensation	3 Months Ended
Equity-based Compensation	Mar. 31, 2014
Equity-based Compensation	'
Equity-based Compensation	'
	9. Equity-based Compensation

	Restricted Stock Awards and Restricted Stock Units

	We record compensation expense equal to the fair value of share-based payments over the vesting periods of the Long-Term Incentive Plan (“LTIP”) awards. We recorded compensation expense from awards granted under our LTIP of $17.9 million and $18.9 million during the three months ended March 31, 2014 and 2013, respectively. The total tax benefit for the three months ended March 31, 2014 and 2013 was $6.1 million and $6.4 million, respectively. Additionally, we expensed a tax shortfall related to equity-based compensation of $0.1 million and nil for the three months ended March 31, 2014 and 2013, respectively. The Company granted both restricted stock awards and restricted stock units with service vesting criteria and granted both restricted stock awards and restricted stock units with a combination of market and service criteria under the LTIP.

	The following table reflects the outstanding restricted stock awards as of March 31, 2014:

				Weighted-		Market / Service		Weighted-
		Service Vesting		Average		Vesting		Average
		Restricted Stock		Grant-Date		Restricted Stock		Grant-Date
		Awards		Fair Value		Awards		Fair Value
		(In thousands)				(In thousands)
	Outstanding at December 31, 2013	6,384		$	16.48	3,438		$	12.95
	Granted	—		—		—		—
	Forfeited	(19	)	18.23		(1	)	13.5
	Vested	(78	)	12.69		—		—
	Outstanding at March 31, 2014	6,287				3,437


	The following table reflects the outstanding restricted stock units as of March 31, 2014:

				Weighted-		Market / Service		Weighted-
		Service Vesting		Average		Vesting		Average
		Restricted Stock		Grant-Date		Restricted Stock		Grant-Date
		Units		Fair Value		Units		Fair Value
		(In thousands)				(In thousands)
	Outstanding at December 31, 2013	2,238		$	10.74	1,858		$	15.59
	Granted	106		10.56		41		15.44
	Forfeited	(42	)	11.97		(12	)	15.43
	Vested	(51	)	11.57		—		—
	Outstanding at March 31, 2014	2,251				1,887


	As of March 31, 2014, total equity-based compensation to be recognized on unvested restricted stock awards and restricted stock units is $104.7 million over a weighted average period of 1.4 years. At March 31, 2014, the Company had approximately 5.2 million shares that remain available for issuance under the LTIP.

	For restricted stock awards with a combination of market and service vesting criteria, the number of common shares to be issued is determined by comparing the Company’s total shareholder return with the total shareholder return of a predetermined group of peer companies over the performance period and can vest in up to 100% of the awards granted. The grant date fair value of these awards ranged from $6.70 to $13.57 per award. The Monte Carlo simulation model utilizes multiple input variables that determine the probability of satisfying the market condition stipulated in the award grant and calculates the fair value of the award. The expected volatility utilized in the model was estimated using our historical volatility and the historical volatilities of our peer companies and ranged from 41.3% to 56.7%. The risk-free interest rate was based on the U.S. treasury rate for a term commensurate with the expected life of the grant and ranged from 0.5% to 1.1%.

	For restricted stock units with a combination of market and service vesting criteria, the number of common shares to be issued is determined by comparing the Company’s total shareholder return with the total shareholder return of a predetermined group of peer companies over the performance period and can vest in up to 200% of the awards granted. The grant date fair value of these awards ranged from $15.44 to $15.81 per award. The Monte Carlo simulation model utilizes multiple input variables that determine the probability of satisfying the market condition stipulated in the award grant and calculates the fair value of the award. The expected volatility utilized in the model was estimated using our historical volatility and the historical volatilities of our peer companies and ranged from 53.0% to 54.0%. The risk-free interest rate was based on the U.S. treasury rate for a term commensurate with the expected life of the grant and ranged from 0.5% to 0.7%.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Taxes	'
Income Taxes	'
	10. Income Taxes

	Income tax expense was $50.8 million and $44.1 million for the three months ended March 31, 2014 and 2013, respectively. The income tax provision consists of U.S. and Ghanaian income and Texas margin taxes.

	The components of income before income taxes were as follows:

		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Bermuda	$	(5,315	)	$	(6,777	)
	United States	3,286			2,370
	Foreign—other	127,781			68,592
	Income before income taxes	$	125,752		$	64,185

	Our effective tax rate for the three months ended March 31, 2014 and 2013 is 40% and 69%, respectively. The effective tax rate for the United States is approximately 45% and 37% for the three months ended March 31, 2014 and 2013, respectively. The effective tax rate in the United States is impacted by the effect of tax shortfalls related to equity-based compensation. The effective tax rate for Ghana is approximately 35% and 37% for the three months ended March 31, 2014 and 2013, respectively. Our other foreign jurisdictions have a 0% effective tax rate because they reside in countries with a 0% statutory rate, or we have experienced losses in those countries and have a full valuation allowance reserved against the corresponding net deferred tax assets.

	The Company has no material unrecognized income tax benefits.

	A subsidiary of the Company files a U.S. federal income tax return and a Texas margin tax return. In addition to the United States, the Company files income tax returns in the countries in which the Company operates. The Company is open to U.S. federal income tax examinations for tax years 2012 through 2013 and to Texas margin tax examinations for the tax years 2009 through 2013. In addition, the Company is open to income tax examinations for years 2004 through 2013 in its significant other foreign jurisdictions (Ghana, Cameroon and Morocco).

	As of March 31, 2014, the Company had no material uncertain tax positions. The Company’s policy is to recognize potential interest and penalties related to income tax matters in income tax expense, but has not accrued any material amounts to date.

Net_Income_Per_Share

Net Income Per Share	3 Months Ended
	Mar. 31, 2014
Net Income Per Share	'
Net Income Per Share	'
	11. Net Income Per Share

	The following table is a reconciliation between net income and the amounts used to compute basic and diluted net income per share and the weighted average shares outstanding used to compute basic and diluted net income per share:

		Three Months Ended
		March 31,
		2014		2013
		(In thousands, except per share data)
	Numerator:
	Net income	$	74,969	$	20,094
	Less: Basic income allocable to participating securities(1)	1,234		512
	Basic net income allocable to common shareholders	73,735		19,582
	Diluted adjustments to income allocable to participating securities(1)	12		2
	Diluted net income allocable to common shareholders	$	73,747	$	19,584
	Denominator:
	Weighted average number of shares used to compute net income per share:
	Basic	377,830		375,284
	Restricted stock awards and units(1)(2)	3,642		367
	Diluted	381,472		375,651
	Net income per share:
	Basic	$	0.2	$	0.05
	Diluted	$	0.19	$	0.05


	(1) Our service vesting restricted stock awards represent participating securities because they participate in nonforfeitable dividends with common equity owners. Income allocable to participating securities represents the distributed and undistributed earnings attributable to the participating securities. Our restricted stock awards with market and service vesting criteria and all restricted stock units are not considered to be participating securities and, therefore, are excluded from the basic net income per common share calculation. Our service vesting restricted stock awards do not participate in undistributed net losses and, therefore, are excluded from the basic net income per common share calculation in periods we are in a net loss position.

	(2) For the three months ended March 31, 2014 and 2013, we excluded 6.4 million and 13.8 million outstanding restricted stock awards, respectively, from the computations of diluted net income per share because the effect would have been anti-dilutive.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
Commitments and Contingencies	'
	12. Commitments and Contingencies

	We are involved in litigation, regulatory examinations and administrative proceedings primarily arising in the ordinary course of our business in jurisdictions in which we do business. Although the outcome of these matters cannot be predicted with certainty, management believes none of these matters, either individually or in the aggregate, would have a material effect upon the Company’s financial position; however, an unfavorable outcome could have a material adverse effect on our results from operations for a specific interim period or year.

	In June 2013, we signed a long-term rig agreement with a subsidiary of Atwood Oceanics, Inc. for the new build drillship “Atwood Achiever.” Currently under construction, the rig is expected to commence drilling operations in the second half of 2014. The rig agreement covers an initial period of three years at a day rate of approximately $0.6 million, with an option to extend the agreement for an additional three-year term. We have entered into a rig sharing agreement, whereby two rig slots (estimated to be 150 days in total during 2015) were assigned to a third-party. The estimated rig delivery date is in the third quarter of 2014.

	The estimated future minimum commitments under this contract as of March 31, 2014, are:

		Payments Due By Year(1)
		Total		2014(2)		2015		2016		2017		2018		Thereafter
		(In thousands)
	Operating leases	$	19,642	$	3,292	$	3,515	$	3,158	$	3,223	$	3,323	$	3,131
	Atwood Achiever drilling rig contract (3)	562,870		91,035		127,925		217,770		126,140		—		—



	(1) Does not include purchase commitments for jointly owned fields and facilities where we are not the operator and excludes commitments for exploration activities, including well commitments, in our petroleum contracts.

	(2) Represents payments for the period from April 1, 2014 through December 31, 2014.

	(3) Commitments calculated using a day rate of $595,000 and an estimated rig delivery date of August 1, 2014. The rig commitments reflect the execution of a rig sharing agreement, whereby two rig slots (estimated to be 150 days in total during 2015) were assigned to a third-party.

Subsequent_Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2014
Subsequent Events	'
Subsequent Events	'
	13. Subsequent Events

	In Morocco, the FA-1 exploration well on the Foum Assaka Offshore block in the Agadir Basin was determined to be non-commercial and accordingly will be plugged and abandoned. BP is funding Kosmos’ share of the FA-1 exploration well, subject to a maximum spend of $120.0 million. As of March 31, 2014, we had not reached the maximum spend. We will pay our proportionate share of costs above the maximum spend, which is not expected to be material and will be expensed as incurred.

	As part of a corporate reorganization, we currently estimate $9.0 million in restructuring charges associated with severance and related benefits will be recognized during the second quarter of 2014.

Accounting_Policies_Policies

Accounting Policies (Policies)	3 Months Ended
Accounting Policies (Policies)	Mar. 31, 2014
Accounting Policies	'
General	'
	General

	The interim-period financial information presented in the consolidated financial statements included in this report is unaudited and, in the opinion of management, includes all adjustments of a normal recurring nature necessary to present fairly the consolidated financial position as of March 31, 2014, the changes in the consolidated statements of shareholders’ equity for the three months ended March 31, 2014, the consolidated results of operations for the three months ended March 31, 2014 and 2013, and consolidated cash flows for the three months ended March 31, 2014 and 2013. The results of the interim periods shown in this report are not necessarily indicative of the final results to be expected for the full year. The consolidated financial statements were prepared in accordance with the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain notes or other financial information that are normally required by Generally Accepted Accounting Principles (“GAAP”) have been condensed or omitted from these interim consolidated financial statements. These consolidated financial statements and the accompanying notes should be read in conjunction with our audited consolidated financial statements for the year ended December 31, 2013, included in our annual report on Form 10-K.
Reclassifications	'
	Reclassifications

	Certain prior period amounts have been reclassified to conform with the current year presentation. Such reclassifications had no impact on our reported net loss, current assets, total assets, current liabilities, total liabilities or shareholders’ equity.
Restricted Cash	'
	Restricted Cash

	In accordance with our commercial debt facility, we are required to maintain a restricted cash balance that is sufficient to meet the payment of interest and fees for the next six-month period. As of March 31, 2014 and December 31, 2013, we had $19.1 million and $18.6 million, respectively, in current restricted cash to meet this requirement. In addition, in accordance with certain of our petroleum contracts, we have posted letters of credit related to performance guarantees for our minimum work obligations. These letters of credit are cash collateralized in accounts held by us and as such are classified as restricted cash. Upon completion of the minimum work obligations and/or entering into the next phase of the petroleum contract, the requirement to post the existing letters of credit will be satisfied and the cash collateral will be released. However, additional letters of credit may be required should we choose to move into the next phase of certain of our petroleum contracts. As of March 31, 2014 and December 31, 2013, we had $1.0 million and $2.9 million, respectively, of current restricted cash and $35.3 million and $31.5 million, respectively, of long-term restricted cash used to cash collateralize performance guarantees related to our petroleum contracts.
Inventories	'
	Inventories

	Inventories consisted of $37.5 million and $45.8 million of materials and supplies and $5.0 million and $1.6 million of hydrocarbons as of March 31, 2014 and December 31, 2013, respectively. The Company’s materials and supplies inventory primarily consists of casing and wellheads and is stated at the lower of cost, using the weighted average cost method, or market.

	Hydrocarbon inventory is carried at the lower of cost, using the weighted average cost method, or market. Hydrocarbon inventory costs include expenditures and other charges incurred in bringing the inventory to its existing condition. Selling expenses and general and administrative expenses are reported as period costs and excluded from inventory costs.
Variable Interest Entity	'
	Variable Interest Entity

	Our wholly owned subsidiary, Kosmos Energy Finance International, is a variable interest entity (“VIE”). The Company is the primary beneficiary of this VIE, which is consolidated in these financial statements.

	Kosmos Energy Finance International’s following assets and liabilities are shown separately on the face of the consolidated balance sheets as of March 31, 2014 and December 31, 2013: current derivatives asset; long-term debt and current and long-term derivatives liabilities. At March 31, 2014, Kosmos Energy Finance International had $18.6 million in cash and cash equivalents; $19.1 million in current restricted cash; $50.0 million deferred financing costs, net; $2.0 million in accrued liabilities and $4.1 million in other long-term liabilities, which are included in the amounts shown on the face of the consolidated balance sheets. At December 31, 2013, Kosmos Energy Finance International had $38.1 million in cash and cash equivalents; $18.6 million in current restricted cash; $0.2 million in prepaid expenses and other; $34.2 million deferred financing costs, net; $1.4 million in accrued liabilities and $8.2 million in other long-term liabilities, which are included in the amounts shown on the face of the consolidated balance sheets.

Property_and_Equipment_Tables

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
Property and Equipment	'
Schedule of property and equipment	'

		March 31,			December 31,
		2014			2013
		(In thousands)
	Oil and gas properties:
	Proved properties	$	832,569		$	801,348
	Unproved properties	555,145			524,257
	Support equipment and facilities	714,803			710,289
	Total oil and gas properties	2,102,517			2,035,894
	Less: accumulated depletion	(571,851		)	(527,832		)
	Oil and gas properties, net	1,530,666			1,508,062

	Other property	32,225			31,658
	Less: accumulated depreciation	(18,070		)	(16,758		)
	Other property, net	14,155			14,900

	Property and equipment, net	$	1,544,821		$	1,522,962

Suspended_Well_Costs_Tables

Suspended Well Costs (Tables)	3 Months Ended
Suspended Well Costs (Tables)	Mar. 31, 2014
Suspended Well Costs	'
Schedule of aging of capitalized exploratory well costs and number of projects for which exploratory well costs were capitalized for more than one year	'

		March 31, 2014		December 31, 2013
		(In thousands, except well counts)
	Exploratory well costs capitalized for a period of one year or less	$	11,456	$	11,426
	Exploratory well costs capitalized for a period one to two years	175,162		229,140
	Exploratory well costs capitalized for a period three to five years	189,335		135,600
	Ending balance	$	375,953	$	376,166
	Number of projects that have exploratory well costs that have been capitalized for a period greater than one year	8		8

Accrued_Liabilities_Tables

Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Liabilities	'
Accrued Liabilities	'

		March 31,		December 31,
		2014		2013
		(In thousands)
	Accrued liabilities:
	Accrued exploration, development and production	$	101,360	$	73,976
	Income taxes	20,463		20,379
	Accrued taxes other than income	16,560		15,188
	Accrued general and administrative expenses	9,462		4,255
	Accrued other	2,679		1,414
		$	150,524	$	115,212

Debt_Tables

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2014
Debt	'
Schedule of estimated repayments of debt	'
	At March 31, 2014, the estimated repayments of debt during the five fiscal year periods and thereafter are as follows:

		Payments Due by Year
		2014(1)		2015		2016		2017		2018		Thereafter
		(In thousands)
	Facility(2)	$	—	$	—	$	—	$	—	$	35,812	$	764,188



	(1) Represents payments for the period April 1, 2014 through December 31, 2014.
	(2) The scheduled maturities of debt are based on the level of borrowings and the estimated future available borrowing base as of March 31, 2014. Any increases or decreases in the level of borrowings or decreases in the available borrowing base would impact the scheduled maturities of debt during the next five years and thereafter.

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
Derivative Financial Instruments (Tables)	Mar. 31, 2014
Derivative Financial Instruments	'
Schedule of oil derivative contracts	'

						Weighted Average Dated Brent Price per Bbl
	Term(1)	Type of Contract		MBbl		Deferred			Swap		Floor		Ceiling		Call
						Premium
						Receivable/
						(Payable)
	2014:00:00
	April - December	Three-way collars		1,125		$	(1.22	)	$	—	$	85	$	115	$	140
	April - December	Three-way collars		753		—			—		85		115.01		140
	April - December	Three-way collars		752		—			—		88.1		110		125
	April - December	Three-way collars		1,129		1.15			—		90		113		135
	April - December	Three-way collars		752		—			—		95		115.47		130
	2015:00:00
	January - December	Three-way collars		1,730		$	(0.43	)	$	—	$	85	$	110	$	135
	January - December	Three-way collars		1,500		(0.80		)	—		90		110		135
	January - December	Swaps with calls		2,000		—			99		—		—		115


	(1) In April 2014, we entered into put contracts for 1.0 MMBbl from January 2016 through December 2016 with a floor price of $85.00 per Bbl. The put contracts are indexed to Dated Brent prices and have a weighted average deferred premium payable of $3.82 per Bbl.
Schedule of interest rate swaps derivative contracts	'
	The following table summarizes our open interest rate swaps as of March 31, 2014, whereby we pay a fixed rate of interest and the counterparty pays a variable LIBOR-based rate:

	Term	Weighted Average			Weighted Average		Floating Rate
	Term	Notional Amount			Fixed Rate		Floating Rate
		(In thousands)
	April 2014 — December 2014	$	133,434		1.99	%	6-month LIBOR
	January 2015 — December 2015	45,319			2.03	%	6-month LIBOR
	January 2016 — June 2016	12,500			2.27	%	6-month LIBOR
Schedule of derivative instruments by balance sheet location	'

				Estimated Fair Value
				Asset (Liability)
				March 31,			December 31,
	Type of Contract	Balance Sheet Location		2014			2013
				(In thousands)
	Derivatives not designated as hedging instruments:
	Derivative assets:
	Commodity	Derivatives assets—current		$	510		$	—

	Derivative liabilities:
	Commodity(1)	Derivatives liabilities—current		(5,738		)	(7,873		)
	Interest rate	Derivatives liabilities—current		(2,369		)	(2,067		)
	Commodity(2)	Derivatives liabilities—long-term		(3,732		)	(3,144		)
	Interest rate	Derivatives liabilities—long-term		(463		)	(667		)
	Total derivatives not designated as hedging instruments			$	(11,792	)	$	(13,751	)


	(1) Includes deferred premiums payable of $0.4 million and $0.1 million related to commodity derivative contracts as of March 31, 2014 and December 31, 2013, respectively.

	(2) Includes deferred premiums payable of $1.6 million and $6.5 million related to commodity derivative contracts as of March 31, 2014 and December 31, 2013, respectively.
Schedule of derivative instruments by location of gain/(loss)	'

				Amount of Gain/(Loss)
				Three Months Ended
				March 31,
	Type of Contract	Location of Gain/(Loss)		2014			2013
				(In thousands)
	Derivatives in cash flow hedging relationships:
	Interest rate(1)	Interest expense		$	406		$	359
	Total derivatives in cash flow hedging relationships			$	406		$	359

	Derivatives not designated as hedging instruments:
	Commodity(2)	Oil and gas revenue		$	(1,526	)	$	4,588
	Commodity	Derivatives, net		2,028			(5,508		)
	Interest rate	Interest expense		(98		)	27
	Total derivatives not designated as hedging instruments			$	404		$	(893	)


	(1) Amounts were reclassified from accumulated other comprehensive income or loss (“AOCI”) into earnings upon settlement.

	(2) Amounts represent the mark-to-market portion of our provisional oil sales contracts.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Measurements	'
Schedule of Company's assets and liabilities that are measured at fair value on a recurring basis	'

		Fair Value Measurements Using:
		Quoted Prices in		Significant Other			Significant
		Active Markets for		Observable Inputs			Unobservable Inputs
		Identical Assets
		(Level 1)		(Level 2)			(Level 3)		Total
		(In thousands)
	March 31, 2014
	Assets:
	Commodity derivatives	$	—	$	510		$	—	$	510
	Liabilities:
	Commodity derivatives	—		(9,470		)	—		(9,470		)
	Interest rate derivatives	—		(2,832		)	—		(2,832		)
	Total	$	—	$	(11,792	)	$	—	$	(11,792	)

	December 31, 2013
	Liabilities:
	Commodity derivatives	$	—	$	(11,017	)	$	—	$	(11,017	)
	Interest rate derivatives	—		(2,734		)	—		(2,734		)
	Total	$	—	$	(13,751	)	$	—	$	(13,751	)

Equitybased_Compensation_Table

Equity-based Compensation (Tables) (LTIP)	3 Months Ended
Equity-based Compensation (Tables) (LTIP)	Mar. 31, 2014
Restricted stock awards	'
Equity-based Compensation	'
Schedule of plan activity	'

				Weighted-		Market / Service		Weighted-
		Service Vesting		Average		Vesting		Average
		Restricted Stock		Grant-Date		Restricted Stock		Grant-Date
		Awards		Fair Value		Awards		Fair Value
		(In thousands)				(In thousands)
	Outstanding at December 31, 2013	6,384		$	16.48	3,438		$	12.95
	Granted	—		—		—		—
	Forfeited	(19	)	18.23		(1	)	13.5
	Vested	(78	)	12.69		—		—
	Outstanding at March 31, 2014	6,287				3,437

Restricted stock units	'
Equity-based Compensation	'
Schedule of plan activity	'
				Weighted-		Market / Service		Weighted-
		Service Vesting		Average		Vesting		Average
		Restricted Stock		Grant-Date		Restricted Stock		Grant-Date
		Units		Fair Value		Units		Fair Value
		(In thousands)				(In thousands)
	Outstanding at December 31, 2013	2,238		$	10.74	1,858		$	15.59
	Granted	106		10.56		41		15.44
	Forfeited	(42	)	11.97		(12	)	15.43
	Vested	(51	)	11.57		—		—
	Outstanding at March 31, 2014	2,251				1,887

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2014
Income Taxes	'
Schedule of components of income before income taxes	'

		Three Months Ended March 31,
		2014			2013
		(In thousands)
	Bermuda	$	(5,315	)	$	(6,777	)
	United States	3,286			2,370
	Foreign—other	127,781			68,592
	Income before income taxes	$	125,752		$	64,185

Net_Income_Per_Share_Tables

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2014
Net Income Per Share	'
Schedule of reconciliation between net income and the amounts used to compute basic and diluted net income per share and the weighted average shares outstanding used to compute basic and diluted net income per share	'

		Three Months Ended
		March 31,
		2014		2013
		(In thousands, except per share data)
	Numerator:
	Net income	$	74,969	$	20,094
	Less: Basic income allocable to participating securities(1)	1,234		512
	Basic net income allocable to common shareholders	73,735		19,582
	Diluted adjustments to income allocable to participating securities(1)	12		2
	Diluted net income allocable to common shareholders	$	73,747	$	19,584
	Denominator:
	Weighted average number of shares used to compute net income per share:
	Basic	377,830		375,284
	Restricted stock awards and units(1)(2)	3,642		367
	Diluted	381,472		375,651
	Net income per share:
	Basic	$	0.2	$	0.05
	Diluted	$	0.19	$	0.05


	(1) Our service vesting restricted stock awards represent participating securities because they participate in nonforfeitable dividends with common equity owners. Income allocable to participating securities represents the distributed and undistributed earnings attributable to the participating securities. Our restricted stock awards with market and service vesting criteria and all restricted stock units are not considered to be participating securities and, therefore, are excluded from the basic net income per common share calculation. Our service vesting restricted stock awards do not participate in undistributed net losses and, therefore, are excluded from the basic net income per common share calculation in periods we are in a net loss position.

	(2) For the three months ended March 31, 2014 and 2013, we excluded 6.4 million and 13.8 million outstanding restricted stock awards, respectively, from the computations of diluted net income per share because the effect would have been anti-dilutive.

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies	'
Schedule of estimated future minimum commitments	'
	The estimated future minimum commitments under this contract as of March 31, 2014, are:

		Payments Due By Year(1)
		Total		2014(2)		2015		2016		2017		2018		Thereafter
		(In thousands)
	Operating leases	$	19,642	$	3,292	$	3,515	$	3,158	$	3,223	$	3,323	$	3,131
	Atwood Achiever drilling rig contract (3)	562,870		91,035		127,925		217,770		126,140		—		—



	(1) Does not include purchase commitments for jointly owned fields and facilities where we are not the operator and excludes commitments for exploration activities, including well commitments, in our petroleum contracts.

	(2) Represents payments for the period from April 1, 2014 through December 31, 2014.

	(3) Commitments calculated using a day rate of $595,000 and an estimated rig delivery date of August 1, 2014. The rig commitments reflect the execution of a rig sharing agreement, whereby two rig slots (estimated to be 150 days in total during 2015) were assigned to a third-party.

Organization_Details

Organization (Details)	3 Months Ended
	Mar. 31, 2014
	segment
Organization	'
Number of reportable segments	1

Accounting_Policies_Details

Accounting Policies (Details) (USD $)	3 Months Ended
Accounting Policies (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Restricted Cash	'	'
Current restricted cash	$20,135,000	$21,475,000
Long-term restricted cash	35,250,000	31,500,000
Inventories	'	'
Materials and supplies inventory	37,500,000	45,800,000
Hydrocarbons inventory	5,000,000	1,600,000
Restricted Cash \| Commercial Debt Facility	'	'
Restricted Cash	'	'
Restricted cash period required as per commercial debt facility to meet interest and commitment fee payments	'6 months	'
Current restricted cash	19,100,000	18,600,000
Restricted Cash \| Petroleum agreements - performance guarantees	'	'
Restricted Cash	'	'
Current restricted cash	1,000,000	2,900,000
Long-term restricted cash	$35,300,000	$31,500,000

Accounting_Policies_Details_2

Accounting Policies (Details 2) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Variable interest entity	'	'	'	'
Cash and cash equivalents	$528,028	$598,108	$497,289	$515,164
Current restricted cash	20,135	21,475	'	'
Prepaid expenses and other	37,494	27,010	'	'
Deferred financing costs, net	55,216	40,111	'	'
Accrued liabilities	150,524	115,212	'	'
Other long-term liabilities	16,093	20,534	'	'
Kosmos Energy Finance International	'	'	'	'
Variable interest entity	'	'	'	'
Cash and cash equivalents	18,600	38,100	'	'
Current restricted cash	19,100	18,600	'	'
Prepaid expenses and other	'	200	'	'
Deferred financing costs, net	50,000	34,200	'	'
Accrued liabilities	2,000	1,400	'	'
Other long-term liabilities	$4,100	$8,200	'	'

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)	3 Months Ended
Property and Equipment (Details) (USD $)	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Oil and gas properties:	'	'	'
Proved properties	$832,569,000	'	$801,348,000
Unproved properties	555,145,000	'	524,257,000
Support equipment and facilities	714,803,000	'	710,289,000
Total oil and gas properties	2,102,517,000	'	2,035,894,000
Less: accumulated depletion	-571,851,000	'	-527,832,000
Oil and gas properties, net	1,530,666,000	'	1,508,062,000
Other property	32,225,000	'	31,658,000
Less: accumulated depreciation	-18,070,000	'	-16,758,000
Other property, net	14,155,000	'	14,900,000
Property and equipment, net	1,544,821,000	'	1,522,962,000
Depletion expense	44,000,000	56,600,000	'
Property and Equipment	'	'	'
Proceeds on sale of assets	34,581,000	'	'
Joint interest billings receivable	102,843,000	'	19,930,000
Gain on the transaction	23,769,000	'	'
Farm-out agreements \| Essaouira Offshore Block	'	'	'
Property and Equipment	'	'	'
Participating interests (as a percent)	30.00%	'	'
Farm-out agreements \| Foum Assaka Offshore Block	'	'	'
Property and Equipment	'	'	'
Participating interests (as a percent)	29.93%	'	'
Farm-out agreements \| Tarhazoute Offshore Block	'	'	'
Property and Equipment	'	'	'
Participating interests (as a percent)	30.00%	'	'
Farm-out agreements \| Cap Boujdour Offshore block	'	'	'
Property and Equipment	'	'	'
Participating interests (as a percent)	55.00%	'	'
BP \| Farm-out agreements \| Essaouira Offshore, Foum Assaka Offshore and Tarhazoute Offshore blocks	'	'	'
Property and Equipment	'	'	'
Number of blocks covered by farm-out agreements	3	'	'
Sale price of assets	56,900,000	'	'
Proceeds on sale of assets	34,600,000	'	'
Joint interest billings receivable	22,300,000	'	'
Gain on the transaction	24,400,000	'	'
Cairn \| Farm-out agreements \| Cap Boujdour Offshore block	'	'	'
Property and Equipment	'	'	'
Amount of shared costs to be paid by third party	$1,500,000	'	'

Suspended_Well_Costs_Details

Suspended Well Costs (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014
In Thousands, unless otherwise specified	project	project	Mahogany East Area	Mahogany East Area	Teak-1 Discovery	Teak-1 Discovery	Teak-2 Discovery	Akasa Discovery	Akasa Discovery	TEN Discoveries	Wawa Discovery
			item	Maximum	item	Maximum	Maximum	item	Maximum	Maximum	Maximum
										Forecast
										item
Aging of capitalized exploratory well costs and number of projects for which exploratory well costs were capitalized for more than one year	'	'	'	'	'	'	'	'	'	'	'
Exploratory well costs capitalized for a period of one year or less	$11,456	$11,426	'	'	'	'	'	'	'	'	'
Exploratory well costs capitalized for a period one to two years	175,162	229,140	'	'	'	'	'	'	'	'	'
Exploratory well costs capitalized for a period three to five years	189,335	135,600	'	'	'	'	'	'	'	'	'
Ending balance	$375,953	$376,166	'	'	'	'	'	'	'	'	'
Number of projects that have exploratory well costs that have been capitalized for a period greater than one year	8	8	'	'	'	'	'	'	'	'	'
Projects with exploratory well costs capitalized for more than one year	'	'	'	'	'	'	'	'	'	'	'
Number of appraisal wells which were drilled	'	'	3	'	2	'	'	'	'	'	'
Submission of PoD to Ghana's Ministry of Energy, period	'	'	'	'6 months	'	'6 months	'6 months	'	'6 months	'	'6 months
Number of appraisal well	'	'	'	'	'	'	'	1	'	'	'
Number of wells developed	'	'	'	'	'	'	'	'	'	24	'

Accrued_Liabilities_Details

Accrued Liabilities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accrued liabilities:	'	'
Accrued exploration, development and production	$101,360	$73,976
Income taxes	20,463	20,379
Accrued taxes other than income	16,560	15,188
Accrued general and administrative expenses	9,462	4,255
Accrued other	2,679	1,414
Accrued liabilities	$150,524	$115,212

Debt_Details

Debt (Details) (USD $)	3 Months Ended		3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Apr. 30, 2013	Mar. 31, 2013	Mar. 31, 2014	Jul. 31, 2013
			Facility	Facility	Facility	Corporate Revolver	Corporate Revolver	Corporate Revolver	Revolving Letter of Credit Facility	Revolving Letter of Credit Facility
				Minimum	Maximum				item
Debt	'	'	'	'	'	'	'	'	'	'
Total commitment	'	'	$1,500,000,000	'	'	'	$300,000,000	$260,000,000	'	$100,000,000
Loss on extinguishment of debt	2,898,000	'	2,900,000	'	'	'	'	'	'	'
Net deferred financing costs	55,216,000	40,111,000	50,000,000	'	'	'	'	'	'	'
Amount outstanding	'	'	800,000,000	'	'	0	'	'	'	'
Undrawn availability	'	'	700,000,000	'	'	300,000,000	'	'	'	'
Applicable margin (as a percent)	'	'	'	3.25%	4.50%	'	'	'	'	'
Variable rate basis	'	'	'LIBOR	'	'	'	'	'	'	'
Interval period for payment of interest	'	'	'6 months	'	'	'	'	'	'	'
Commitment fee percentage of the then-applicable margin when commitment is available for utilization	'	'	40.00%	'	'	'	'	'	'	'
Commitment fee percentage of the then-applicable margin when commitment is not available for utilization	'	'	20.00%	'	'	'	'	'	'	'
Adjustment in estimate of deferred interest	'	'	4,500,000	'	'	'	'	'	'	'
Revolving-credit sublimit amount after March 31, 2018	'	'	500,000,000	'	'	'	'	'	'	'
Availability period of revolving-credit sublimit	'	'	'1 month	'	'	'	'	'	'	'
Amount outstanding under letters of credit	'	'	0	'	'	'	'	'	'	'
Other disclosures	'	'	'	'	'	'	'	'	'	'
Additional commitments	'	'	'	'	'	'	'	'	'	50,000,000
Number of letters of credit	'	'	'	'	'	'	'	'	7	'
Restricted cash	35,250,000	31,500,000	'	'	'	'	'	'	35,300,000	'
Scheduled maturities of debt during the five year period and thereafter	'	'	'	'	'	'	'	'	'	'
2018	'	'	35,812,000	'	'	'	'	'	'	'
Thereafter	'	'	$764,188,000	'	'	'	'	'	'	'

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Details) (Price risk derivatives)	3 Months Ended							1 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2014	Apr. 30, 2014	Mar. 31, 2014
	Three-way Collars	Three-way Collars	Three-way collars	Three-way collars	Three-way collars	Three-way collars	Three-way collars	Put contracts	Swaps with calls
	Term April 2014 to December 2014	Term January 2015 to December 2015	Term April 2014 to December 2014	Term January 2015 to December 2015	Term April 2014 to December 2014	Term April 2014 to December 2014	Term April 2014 to December 2014	Term January 2016 to December 2016	Term January 2015 to December 2015
	MBbls	MBbls	MBbls	MBbls	MBbls	MBbls	MBbls	MBbls	MBbls
Derivative Financial Instruments	'	'	'	'	'	'	'	'	'
Volumes (in MBbl)	1,125	1,730	753	1,500	752	1,129	752	1,000	2,000
Weighted average deferred premium receivable/(payable) per Bbl	-1.22	-0.43	1.15	-0.8	1.15	1.15	1.15	-3.82	'
Weighted average swap price per Bbl	'	'	'	'	'	'	'	'	99
Weighted average floor price per Bbl	85	85	85	90	88.1	90	95	85	'
Weighted average ceiling price per Bbl	115	110	115.01	110	110	113	115.47	'	'
Weighted average call price per Bbl	140	135	140	135	125	135	130	'	115

Derivative_Financial_Instrumen3

Derivative Financial Instruments (Details 2) (Interest Rate Swap, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Term April 2014 to December 2014	'
Derivative Financial Instruments	'
Weighted Average Notional Amount	$133,434
Weighted Average Fixed Rate (as a percent)	1.99%
Floating Rate	'6-month LIBOR
Term January 2015 to December 2015	'
Derivative Financial Instruments	'
Weighted Average Notional Amount	45,319
Weighted Average Fixed Rate (as a percent)	2.03%
Floating Rate	'6-month LIBOR
Term January 2016 to June 2016	'
Derivative Financial Instruments	'
Weighted Average Notional Amount	$12,500
Weighted Average Fixed Rate (as a percent)	2.27%
Floating Rate	'6-month LIBOR

Derivative_Financial_Instrumen4

Derivative Financial Instruments (Details 3) (USD $)	3 Months Ended	12 Months Ended
Derivative Financial Instruments (Details 3) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Derivative instruments, Balance Sheet Location	'	'
Derivatives assets - current	$510,000	'
Derivatives liabilities - current	-8,107,000	-9,940,000
Derivatives liabilities - long-term	-4,195,000	-3,811,000
Not designated as hedging instruments	'	'
Derivative instruments, Balance Sheet Location	'	'
Total	-11,792,000	-13,751,000
Commodity derivatives \| Not designated as hedging instruments	'	'
Derivative instruments, Balance Sheet Location	'	'
Derivatives assets - current	510,000	'
Derivatives liabilities - current	-5,738,000	-7,873,000
Derivatives liabilities - long-term	-3,732,000	-3,144,000
Deferred premiums payable related to commodity derivative contracts	400,000	100,000
Deferred premiums payable related to commodity derivative contracts	1,600,000	6,500,000
Interest rate contracts \| Not designated as hedging instruments	'	'
Derivative instruments, Balance Sheet Location	'	'
Derivatives liabilities - current	-2,369,000	-2,067,000
Derivatives liabilities - long-term	($463,000)	($667,000)

Derivative_Financial_Instrumen5

Derivative Financial Instruments (Details 4) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Derivative instruments, Location of Gain/(Loss)	'	'
Amount of Gain/(Loss), derivatives not designated as hedging instruments	$404	($893)
Commodity derivatives \| Derivatives, net	'	'
Derivative instruments, Location of Gain/(Loss)	'	'
Amount of Gain/(Loss), derivatives not designated as hedging instruments	2,028	-5,508
Commodity derivatives \| Commodity, mark-to-market portion of provisional oil sales contract portion \| Oil and gas revenue	'	'
Derivative instruments, Location of Gain/(Loss)	'	'
Amount of Gain/(Loss), derivatives not designated as hedging instruments	-1,526	4,588
Interest rate contracts \| Interest expense	'	'
Derivative instruments, Location of Gain/(Loss)	'	'
Amount of Gain/(Loss), derivatives not designated as hedging instruments	-98	27
Derivatives in cash flow hedging relationships	'	'
Derivative instruments, Location of Gain/(Loss)	'	'
Total derivatives in cash flow hedging relationships	406	359
Derivatives in cash flow hedging relationships \| Interest rate contracts \| Interest expense	'	'
Derivative instruments, Location of Gain/(Loss)	'	'
Amount of Gain/(Loss) reclassified from AOCI into earnings	$406	$359

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (Recurring basis, USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Level 2	'	'
Liabilities:	'	'
Total fair value, net	($11,792)	($13,751)
Level 2 \| Commodity derivatives	'	'
Assets:	'	'
Derivative asset, fair value	510	'
Liabilities:	'	'
Derivative liability, fair value	-9,470	-11,017
Level 2 \| Interest rate derivatives	'	'
Liabilities:	'	'
Derivative liability, fair value	-2,832	-2,734
Total	'	'
Liabilities:	'	'
Total fair value, net	-11,792	-13,751
Total \| Commodity derivatives	'	'
Assets:	'	'
Derivative asset, fair value	510	'
Liabilities:	'	'
Derivative liability, fair value	-9,470	-11,017
Total \| Interest rate derivatives	'	'
Liabilities:	'	'
Derivative liability, fair value	($2,832)	($2,734)

Equitybased_Compensation_Detai

Equity-based Compensation (Details) (USD $)

3 Months Ended

34 Months Ended

3 Months Ended

34 Months Ended

3 Months Ended

In Millions, except Share data, unless otherwise specified

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

LTIP

Service Vesting Restricted Stock Awards

Market/Service Vesting Restricted Stock Awards

Service Vesting Restricted Stock Units

Market/Service Vesting Restricted Stock Units

Restricted Stock Awards and Restricted Stock Units

LTIP

Minimum

Maximum

LTIP

Minimum

Maximum

LTIP

Compensation agreement

Compensation expense recognized

$17.90

$18.90

Tax benefit

6.1

6.4

Tax shortfall related to equity-based compensation

0.1

Outstanding unvested awards activity

Outstanding at the beginning of the period (in shares)

6,384,000

3,438,000

2,238,000

1,858,000

Granted (in shares)

106,000

41,000

Forfeited (in shares)

-19,000

-1,000

-42,000

-12,000

Vested (in shares)

-78,000

-51,000

Outstanding at the end of the period (in shares)

6,287,000

3,437,000

2,251,000

1,887,000

Weighted-Average Grant-Date Fair Value

Outstanding at beginning of the period (in dollars per share)

$16.48

$12.95

$10.74

$15.59

Granted (in dollars per share)

$6.70

$13.57

$10.56

$15.44

$15.81

Forfeited (in dollars per share)

$18.23

$13.50

$11.97

$15.43

Vested (in dollars per share)

$12.69

$11.57

Compensation expense not yet recognized

$104.70

Weighted average period over which compensation expense is to be recognized

'1 year 4 months 24 days

Other disclosures

Number of shares remaining available for grant

5,200,000

Vesting percentage of the awards granted

100.00%

200.00%

Significant assumptions used to calculate fair values

Expected volatility (as a percent)

41.30%

56.70%

53.00%

54.00%

Risk-free interest rate (as a percent)

0.50%

1.10%

0.50%

0.70%

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Income Taxes	'	'
Income tax expense	$50,783	$44,091
Income before income taxes	125,752	64,185
Effective tax rate (as a percent)	40.00%	69.00%
Bermuda	'	'
Income Taxes	'	'
Income before income taxes	-5,315	-6,777
United States	'	'
Income Taxes	'	'
Income before income taxes	3,286	2,370
Effective tax rate (as a percent)	45.00%	37.00%
Foreign-other	'	'
Income Taxes	'	'
Income before income taxes	$127,781	$68,592
Effective tax rate (as a percent)	0.00%	'
Statutory tax rate (as a percent)	0.00%	'
Ghana	'	'
Income Taxes	'	'
Effective tax rate (as a percent)	35.00%	37.00%

Net_Income_Per_Share_Details

Net Income Per Share (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Numerator:	'	'
Net income	$74,969	$20,094
Less: Basic income allocable to participating securities	1,234	512
Basic net income allocable to common shareholders	73,735	19,582
Diluted adjustments to income allocable to participating securities	12	2
Diluted net income allocable to common shareholders	$73,747	$19,584
Weighted average number of shares used to compute net income per share:	'	'
Basic (in shares)	377,830,000	375,284,000
Restricted stock awards and units (in shares)	3,642,000	367,000
Diluted (in shares)	381,472,000	375,651,000
Net income per share:	'	'
Basic (in dollars per share)	$0.20	$0.05
Diluted (in dollars per share)	$0.19	$0.05
Outstanding restricted stock awards excluded from the computations of diluted net income per share (in shares)	6,400,000	13,800,000

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	1 Months Ended	3 Months Ended
	Jun. 30, 2013	Mar. 31, 2014
	Jun. 30, 2013	item
Operating leases	'	'
Future minimum rental commitments	'	'
Total	'	$19,642,000
2014	'	3,292,000
2015	'	3,515,000
2016	'	3,158,000
2017	'	3,223,000
2018	'	3,323,000
Thereafter	'	3,131,000
Atwood Achiever drilling rig contract	'	'
Offshore drilling rig contract commitments	'	'
Drilling rig contract period	'3 years	'
Initial rig rate per day	600,000	'
Optional extension period	'3 years	'
Number of rig slots taken by third-party	'	2
Estimated number of days of rig slots assigned to third party	'	'150 days
Future minimum rental commitments	'	'
Total	'	562,870,000
2014	'	91,035,000
2015	'	127,925,000
2016	'	217,770,000
2017	'	126,140,000
Rig rate per day	'	$595,000

Subsequent_Events_Details

Subsequent Events (Details) (Subsequent event, USD $)	3 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014
		Foum Assaka Offshore Block
		BP
Subsequent events	'	'
Maximum spend for exploration costs	'	$120
Corporate reorganization, current estimate of restructuring charges associated with severance and related benefits	$9	'