Cobalt International Energy 10-Q 3 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2015shares
Document and Entity Information
Entity Registrant Name	Cobalt International Energy, Inc.
Entity Central Index Key	1,471,261
Document Type	10-Q
Document Period End Date	Sep. 30, 2015
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	414,533,629
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 100,447	$ 246,704
Restricted cash and cash equivalents	252,950
Joint interest and other receivables	91,666	13,575
Prepaid expenses and other current assets	51,549	3,842
Inventory	21,718	35,093
Short-term investments	1,235,350	1,530,206
Current assets held for sale	1,736,559	173,714
Total current assets	3,490,239	2,003,134
Property, plant, and equipment:
Oil and gas properties, successful efforts method of accounting, net of accumulated depletion of $-0-	1,051,373	711,238
Other property and equipment, net of accumulated depreciation and amortization of $6,639 and $5,245, as of September 30, 2015 and December 31, 2014, respectively	2,480	3,416
Total property, plant, and equipment, net	1,053,853	714,654
Long-term investments		326,047
Deferred income taxes	32,299	30,334
Other assets	62,045	49,032
Long-term assets held for sale		1,327,661
Total assets	4,638,436	4,450,862
Current liabilities:
Trade and other accounts payable		70
Accrued liabilities	191,748	98,016
Deferred Angola sales proceeds	250,000
Deferred income taxes	32,299	30,334
Current liabilities held for sale	240,383	175,180
Total current liabilities	714,430	303,600
Long-term debt	1,992,499	1,928,528
Asset retirement obligations	3,069
Other long-term liabilities	2,049	2,172
Long-term liabilities held for sale		102,296
Total long-term liabilities	1,997,617	2,032,996
Stockholders' Equity:
Common stock, $0.01 par value per share; 2,000,000,000 shares authorized, 408,558,174 and 408,505,079 issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	4,085	4,085
Additional paid-in capital	4,157,498	4,137,803
Accumulated deficit	(2,235,194)	(2,027,622)
Total stockholders' equity	1,926,389	2,114,266
Total liabilities and stockholders' equity	$ 4,638,436	$ 4,450,862

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets
Oil and gas properties, successful efforts method of accounting, accumulated depletion (in dollars)	$ 0	$ 0
Other property and equipment, accumulated depreciation and amortization (in dollars)	$ 6,369	$ 5,245
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common stock, shares issued	408,558,174	408,505,079
Common stock, shares outstanding	408,558,174	408,505,079

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating costs and expenses:
Seismic and exploration	$ 10,392	$ 9,870	$ 35,726	$ 18,180
Dry hole expense and impairment	10,880	17,410	38,310	71,034
General and administrative	14,848	17,818	53,015	38,016
Depreciation and amortization	346	410	1,125	1,277
Total operating costs and expenses	36,466	45,508	128,176	128,507
Operating income (loss)	(36,466)	(45,508)	(128,176)	(128,507)
Other income (expense):
Gain on sale of assets	7		2,632
Interest income	1,475	1,895	4,588	4,274
Interest expense	(14,703)	(23,463)	(52,565)	(52,630)
Total other income (expense)	(13,221)	(21,568)	(45,345)	(48,356)
Net income (loss) from continuing operations before income tax	(49,687)	(67,076)	(173,521)	(176,863)
Net income (loss) from continuing operations	(49,687)	(67,076)	(173,521)	(176,863)
Net income (loss) from discontinued operations, net of income tax	(9,477)	(75,453)	(34,051)	(117,336)
Net income (loss)	$ (59,164)	$ (142,529)	$ (207,572)	$ (294,199)
Basic and diluted income (loss) per share from continuing operations (in dollars per share)	$ (0.12)	$ (0.16)	$ (0.42)	$ (0.43)
Basic and diluted income (loss) per share from discontinued operations (in dollars per share)	(0.02)	(0.19)	(0.08)	(0.29)
Basic and diluted income (loss) per share (in dollars per share)	$ (0.14)	$ (0.35)	$ (0.50)	$ (0.72)
Basic and diluted weighted average common shares outstanding (in shares)	408,545,467	407,095,514	408,525,438	407,058,930

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Changes in Stockholders? Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Balance at Dec. 31, 2014	$ 4,085	$ 4,137,803	$ (2,027,622)	$ 2,114,266
Equity based compensation		19,695		19,695
Net income (loss)			(207,572)	(207,572)
Balance at Sep. 30, 2015	$ 4,085	$ 4,157,498	$ (2,235,194)	$ 1,926,389

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows provided from operating activities
Net income (loss)	$ (207,572)	$ (294,199)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	1,125	1,277
Gain on sale of assets	(2,632)
Loss from discontinued operations	34,051	117,336
Dry hole expense and impairment of unproved properties	38,310	71,034
Equity based compensation	19,695	23,102
Amortization of premium (accretion of discount) on investments	11,984	14,506
Amortization of debt discount and debt issuance costs	66,977	49,944
Changes in operating assets and liabilities:
Joint interest and other receivables	(77,217)	44,522
Inventory	13,257	(6,025)
Prepaid expense and other current assets	(47,706)	36,385
Deferred charges and other	(11,994)	15,188
Trade and other accounts payable	(70)	(19,770)
Accrued liabilities and other	(55,666)	(54,116)
Net cash provided by (used in) operating activities ? continuing operations	(217,458)	(816)
Net cash provided by (used in) operating activities ? discontinued operations	(11,685)	(139,020)
Net cash provided by (used in) operating activities	(229,143)	(139,836)
Cash flows from investing activities
Capital expenditures for oil and gas properties	(35,190)	(27,784)
Capital expenditures for other property and equipment	(188)	(407)
Exploratory wells drilling in process	(188,160)	(95,696)
Change in restricted funds	(48,999)	(112,434)
Proceeds from maturity of investment securities	1,396,756	1,293,659
Purchase of investment securities	(742,666)	(1,936,269)
Net cash provided by (used in) investing activities ? continuing operations	381,553	(878,931)
Net cash provided by (used in) investing activities ? discontinued operations	(294,642)	(260,641)
Net cash provided by (used in) investing activities	86,911	(1,139,572)
Cash flows from financing activities
Proceeds from debt offering, net of costs		1,269,778
Payment of debt issuance costs	(4,025)
Proceeds from stock option exercises		33
Payments for common stock withheld for taxes on equity based compensation		(631)
Net cash provided by (used in) financing activities	(4,025)	1,269,180
Net increase (decrease) in cash and cash equivalents	(146,257)	(10,228)
Cash and cash equivalents, beginning of period	246,704	165,663
Cash and cash equivalents, end of period	100,447	155,435
Cash paid for interest	39,065	18,113
Non-cash disclosures
Changes in accrued capital expenditures	(117,875)	(43,907)
Transfer of investment securities from restricted funds	$ 46,049
Transfer of investment securities to restricted funds		$ (155,105)

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies General Cobalt International Energy, Inc. (the "Company") is an independent exploration and production company with operations in the deepwater U.S. Gulf of Mexico and offshore Angola and Gabon in West Africa. On August 22, 2015, Cobalt International Energy Angola Ltd., a wholly-owned subsidiary of the Company, executed a purchase and sale agreement with Sociedade Nacional de Combustíveis de Angola—Empresa Pública ("Sonangol") for the sale by the Company to Sonangol of the entire issued and outstanding share capital of its indirect wholly-owned subsidiaries CIE Angola Block 20 Ltd. and CIE Angola Block 21 Ltd., which respectively hold the Company's 40% working interest in each of Block 20 and Block 21 offshore Angola (the "Angola Transaction"). The Angola Transaction is subject to Angolan government approvals. Following the transfer of the share capital of CIE Angola Block 20 Ltd. and CIE Angola Block 21 Ltd., the Company will also relinquish its working interest in Block 9 offshore Angola to Sonangol. The Company's working interests in Blocks 9, 20, and 21 offshore Angola have been classified as "held for sale" on the consolidated balance sheet. The results of operations associated with Blocks 9, 20 and 21 offshore Angola have been presented as discontinued operations in the accompanying consolidated statement of operations. Historically, the Company's Angolan subsidiaries constituted a significant portion of its West Africa segment. The Company's operations in Gabon, which are deemed immaterial, have been combined with its United States segment and are reported as one segment. The terms "Company," "Cobalt," "we," "us," "our," "ours," and similar terms refer to Cobalt International Energy, Inc. unless the context indicates otherwise. Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the financial statements of Cobalt International Energy, Inc. and all of its wholly-owned subsidiaries. All significant intercompany transactions and amounts have been eliminated for all periods presented. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles ("GAAP") for interim financial information and the appropriate rules and regulations of the Securities and Exchange Commission ("SEC"). Accordingly, the condensed consolidated financial statements do not include all of the information and footnote disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for interim periods are not necessarily indicative of the results that may be presented for the entire year. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2014. Recently Issued Accounting Standards In April 2015, the FASB amended Accounting Standard Codification Subtopic No. 835-30, Interest—Imputation of Interest (the "ASC Subtopic 835-30"). The amendments require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments. The amendments under ASC Subtopic 835-30 are effective for financial statements issued for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. However, early adoption is permitted for financial statements that have not been previously issued. The Company expects to comply with the amendments to ASC Subtopic 835-30 for the financial statements at its effective date beginning after December 15, 2015. We do not expect the adoption of ASC 835-30 to have a material impact on the Company's financial statements. Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates made by the Company include (i) accruals related to expenses, (ii) assumptions used in estimating fair value of equity based awards and the fair value of the liability component of the convertible senior notes and (iii) assumptions used in impairment testing. Although the Company believes these estimates are reasonable, actual results could differ from these estimates. Investments The Company's policy on accounting for its investments, which consist entirely of debt securities, is based on the accounting guidance relating to " Accounting for Certain Investments in Debt and Equity Securities ." The Company considers all highly liquid interest-earning investments with a maturity of three months or less at the date of purchase to be cash equivalents. Investments with original maturities of greater than three months and remaining maturities of less than one year are classified as short-term investments. Investments with maturities beyond one year are classified as long-term investments. The debt securities are carried at amortized cost, which approximates fair market value as of September 30, 2015 and December 31, 2014 and are classified as held-to-maturity as the Company has the positive intent and ability to hold them until they mature. The net carrying value of held-to-maturity securities is adjusted for amortization of premiums and accretion of discounts to maturity over the life of the securities. Income related to these securities is reported as a component of interest income in the Company's condensed consolidated statement of operations. See Note 5—Investments . Investments are considered to be impaired when a decline in fair value is determined to be other-than-temporary. The Company conducts a regular assessment of its debt securities with unrealized losses to determine whether securities have other-than-temporary impairment ("OTTI"). This assessment considers, among other factors, the nature of the securities, credit rating or financial condition of the issuer, the extent and duration of the unrealized loss, market conditions and whether the Company intends to sell or whether it is more likely than not that the Company will be required to sell the debt securities. As of September 30, 2015 and December 31, 2014, the Company has no OTTI in its debt securities. Asset Retirement Obligation The Company expects to have significant obligations under its lease agreements and federal regulation to remove its equipment and restore land or seabed at the end of oil and natural gas production operations. These asset retirement obligations ("ARO") are primarily associated with plugging and abandoning wells and removing and disposing of offshore oil and natural gas platforms. Estimating the future restoration and removal cost is difficult and requires the Company to make estimates and judgments because most of the removal obligations are many years in the future and contracts and regulation often have vague descriptions of what constitutes removal. Asset removal technologies and cost are constantly changing, as are regulatory, political, environmental, safety and public relations considerations. Pursuant to the accounting guidance relating to " Assets Retirement Obligations ", the Company is required to record a separate liability for the discounted present value of its asset retirement obligations, with an offsetting increase to the related oil and natural gas properties representing asset retirement costs on the balance sheet. The cost of the related oil and natural gas asset, including the asset retirement cost, is depreciated over the useful life of the asset. The asset retirement obligation is recorded at its estimated fair value, measured by reference to the expected future cash outflows required to satisfy the retirement obligation discounted at the Company's credit-adjusted risk-free interest rate. Accretion expense is recognized over time as the discounted liability is accreted to its expected settlement value. Inherent to the present value calculation are numerous estimates, assumptions and judgments, including the ultimate settlement amounts, inflation factors, credit adjusted risk-free rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. To the extent future revisions to these assumptions impact the present value of the abandonment liability, the Company will make corresponding adjustments to both the asset retirement obligation and the related oil and natural gas property asset balance. Increases in the discounted abandonment liability resulting from the passage of time will be reflected as additional accretion expense in the consolidated statement of operations. During the quarterly period ended September 30, 2015, the Company recognized a retirement obligation for its Heidelberg field. The following summarizes the changes in the asset retirement obligation for the nine months ended September 30, 2015: September 30, 2015 ($ in thousands) Beginning of period — Liabilities incurred Accretion — ​ ​ ​ ​ ​ End of period $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Capitalized Interest For exploration and development projects that have not commenced production, interest is capitalized as part of the historical cost of developing and constructing assets. Capitalized interest is determined by multiplying the Company's weighted-average borrowing cost on debt by the average amount of qualifying costs incurred. Once an asset subject to interest capitalization is completed and placed in service, the associated capitalized interest is expensed through depreciation or impairment. See Note 7—Property, Plant, and Equipment and Note 9—Long-term Debt . Earnings (Loss) Per Share Basic income (loss) per share was calculated by dividing net income or loss applicable to common shares by the weighted average number of common shares outstanding during the periods presented. The calculation of diluted income (loss) per share includes the potential dilutive impact of non-vested restricted stock, non-vested restricted stock units, outstanding stock options, the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024 during the period, unless their effect is anti-dilutive. For the three months and nine months ended September 30, 2015, 9,861,834 shares of non-vested restricted stock, non-vested restricted stock units, outstanding stock options, the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024, were excluded from the diluted income (loss) per share calculation because they were anti-dilutive. For the three months and nine months ended September 30, 2014, 8,643,212 shares of non-vested restricted stock, non-vested restricted stock units, outstanding stock options and the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024, were excluded from the diluted income (loss) per share because they are anti-dilutive.

Cash and Cash Equivalents

Cash and Cash Equivalents	9 Months Ended
	Sep. 30, 2015
Cash and Cash Equivalents.
Cash and Cash Equivalents	2. Cash and Cash Equivalents Cash and cash equivalents consisted of the following: September 30, 2015 December 31, 2014 ($ in thousands) Cash at banks $ $ Money market funds Held-to-maturity securities(1) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) These securities mature three months or less from the date of purchase.

Restricted Cash and Cash Equiva

Restricted Cash and Cash Equivalents	9 Months Ended
	Sep. 30, 2015
Restricted Cash and Cash Equivalents
Restricted Cash and Cash Equivalents	3. Restricted Cash and Cash Equivalents Restricted cash and cash equivalents consisted of the following: September 30, 2015 December 31, 2014 ($ in thousands) Angolan sale proceeds $ — American Express Bank pledge agreement — Citibank commercial card agreement — ​ ​ ​ ​ ​ ​ ​ ​ Total restricted funds(1) $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Pursuant to the purchase and sale agreement governing the Angola Transaction, the Company received the First Payment of $250 million during the quarterly period ended September 30, 2015. See Note 10—Angola Transaction . These funds are contractually restricted by the purchase and sale agreement pending the closing of the Angola Transaction. In addition, as of September 30, 2015, approximately $3.0 million was held in collateral accounts established to pledge funds for security of obligations under the American Express Bank Pledge Agreement and the Citibank Commercial Card Agreement. As of September 30, 2015, the Angolan sales proceeds and collateral in these accounts were invested in cash, certificates of deposit, commercial paper, and money market funds, resulting in a net carrying value of approximately $253.0 million. The contractual maturities of these securities are within ninety days.

Joint Interest and Other Receiv

Joint Interest and Other Receivables	9 Months Ended
	Sep. 30, 2015
Joint Interest and Other Receivables
Joint Interest and Other Receivables	4. Joint Interest and Other Receivables Joint interest and other receivables result primarily from billing shared costs under the respective operating agreements to the Company's partners. These are usually settled within 30 days of the invoice date. As of September 30, 2015 and December 31, 2014, the balance in joint interest and other receivables consisted of the following: September 30, 2015 December 31, 2014 ($ in thousands) Partners in the U.S. Gulf of Mexico $ $ Accrued interest on investment securities Other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Investments

Investments	9 Months Ended
	Sep. 30, 2015
Investments
Investments	5. Investments The Company's investments in held-to-maturity securities, which are recorded at amortized cost which approximates fair market value, were as follows as of September 30, 2015 and December 31, 2014: September 30, 2015 December 31, 2014 ($ in thousands) Corporate securities $ $ Commercial paper U.S. Agency securities Certificates of deposit ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company's condensed consolidated balance sheet included the following held-to-maturity securities: September 30, 2015 December 31, 2014 ($ in thousands) Cash and cash equivalents $ $ Short-term investments Restricted cash and cash equivalents — Long-term investments — ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The contractual maturities of these held-to-maturity securities as of September 30, 2015 and December 31, 2014 were as follows: September 30, 2015 December 31, 2014 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value ($ in thousands) Within 1 year $ $ $ $ After 1 year — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2015
Fair Value Measurements
Fair Value Measurements	6. Fair Value Measurements The fair values of the Company's cash and cash equivalents, joint interest and other receivables, short-term restricted funds and investments approximate their carrying amounts due to their short-term duration. The hierarchy below lists three levels of fair value based on the extent to which inputs used in measuring fair value are observable in the market. The Company categorizes each of its fair value measurements as applicable to one of these three levels based on the lowest level input that is significant to the fair value measurement in its entirety. The levels are: Level 1—Quoted prices in active markets that are accessible at the measurement date for identical assets or liabilities. This category includes the Company's cash and money market funds. Level 2—Quoted prices in non-active markets or in active markets for similar assets or liabilities, and inputs other than quoted prices that are observable, for the asset or liability, either directly or indirectly, for substantially the full contractual term of the asset or liability being measured. This category includes the Company's U.S. Treasury bills, U.S. Treasury notes, commercial paper, U.S. agency securities, corporate bonds, and certificates of deposits. Level 3—Inputs that are generally unobservable and typically reflect management's estimate of assumptions that market participants would use in pricing the asset or liability. The Company does not currently have any financial instruments categorized as Level 3. The following tables summarize the Company's significant financial instruments measured on a recurring basis as categorized by the fair value measurement hierarchy: Level 1 Level 2 Carrying Value Fair Value(1) Carrying Value Fair Value(1) Balance as of September 30, 2015 ($ in thousands) Cash and cash equivalents: Cash $ $ $ — $ — $ Money market funds — — Commercial paper — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted cash and cash equivalents: Money market funds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-term investments: U.S. Agency securities — — Corporate bonds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term investments: Corporate bonds — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Carrying Value Fair Value(1) Carrying Value Fair Value(1) Balance as of December 31, 2014 ($ in thousands) Cash and cash equivalents: Cash $ $ $ — $ — $ Money market funds — — Commercial paper — — Corporate bonds ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-term investments: U.S. Agency securities — — Corporate bonds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term investments: Corporate bonds — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) As of September 30, 2015 and December 31, 2014, the Company did not record any OTTI on these assets.

Property, Plant, and Equipment

Property, Plant, and Equipment	9 Months Ended
	Sep. 30, 2015
Property, Plant, and Equipment
Property, Plant, and Equipment	7. Property, Plant, and Equipment Property, plant, and equipment is stated at cost less accumulated depreciation/amortization and consisted of the following: Estimated Useful Life (Years) September 30, 2015 December 31, 2014 ($ in thousands) Oil and Gas Properties: Proved properties: Well and development costs $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total proved properties ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unproved properties: Oil and gas leasehold Less: accumulated valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exploration wells in process ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total unproved properties ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total oil and gas properties, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Property and Equipment: Computer equipment and software 3 Office equipment and furniture 3 - 5 Leasehold improvements 3 - 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other property and equipment, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property, plant, and equipment, net $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The Company recorded $0.3 million and $0.4 million of depreciation and amortization expense for the three months ended September 30, 2015 and 2014, respectively, and $1.1 million and $1.3 million for the nine months ended September 30, 2015 and 2014, respectively. Proved Oil and Gas Properties The Heidelberg project was formally sanctioned for development in mid-2013. As a result of the project sanction, the Company reclassified its Heidelberg exploration well costs to proved property well and development costs and these costs will be amortized when the related proved developed reserves are produced. During the quarter ended March 31, 2015, the Company assigned its 9.375% ownership interest in the Heidelberg prospect to its wholly owned subsidiary, Cobalt GOM #1 LLC ("GOM #1"). As a result, the carrying value of the costs capitalized for all the Heidelberg projects as of March 31, 2015 were transferred to GOM #1. GOM #1 was established to secure the Heidelberg assets creating a first priority lien in the Company's interest in preparation for debt instruments to fund the Heidelberg development project. As of September 30, 2015, the well and development costs consist of $129.3 million relating to exploration, appraisal and development well costs and $189.5 million for costs associated with field development. As of December 31, 2014, the well and development costs consist of $51.1 million relating to exploration, appraisal and development well costs and $132.1 million for costs associated with field development. Unproved Oil and Gas Properties As of September 30, 2015 and December 31, 2014, the Company has the following unproved property acquisition costs, net of valuation allowance on the consolidated balance sheets: September 30, 2015 December 31, 2014 ($ in thousands) Individual oil and gas leaseholds with carrying value greater than $1 million $ $ Individual oil and gas leaseholds with carrying value less than $1 million ​ ​ ​ ​ ​ ​ ​ ​ Accumulated valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total oil and gas leasehold ​ ​ ​ ​ ​ ​ ​ ​ Capitalized Exploration Well Costs If an exploration well provides evidence as to the existence of sufficient quantities of hydrocarbons to justify evaluation for potential development, drilling costs associated with the well are initially capitalized, or suspended, pending a determination as to whether a commercially sufficient quantity of proved reserves can be attributed to the area as a result of drilling. This determination may take longer than one year in certain areas (generally, deepwater and international locations) depending upon, among other things, (i) the amount of hydrocarbons discovered, (ii) the outcome of planned geological and engineering studies, (iii) the need for additional appraisal drilling activities to determine whether the discovery is sufficient to support an economic development plan and (iv) the requirement for government sanctioning in international locations before proceeding with development activities. The following tables reflect the Company's net changes in and the cumulative costs of capitalized exploration well costs (excluding any related leasehold costs): September 30, 2015 December 31, 2014 ($ in thousands) Beginning of period $ $ Additions to capitalized exploration Exploration well costs Capitalized interest Reclassifications to wells, facilities, and equipment based on determination of proved reserves — — Amounts charged to expense(1) ) ) ​ ​ ​ ​ ​ ​ ​ ​ End of period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The amount of $29.5 million charged to expense for the nine months ended September 30, 2015 primarily represents impairment charges of approximately $22.3 million related to the North Platte #2 appraisal well and impairment charges of approximately $6.6 million related to the lowest portion of the Shenandoah #4 appraisal well. The North Platte #2 appraisal well was plugged and abandoned due to a seal failure in the riser connection system. The well was at a depth of 20,701 feet when the problem with the riser was detected. The Company is continuing to assess what additional impairment charges or other liabilities, including any environmental liabilities, might be incurred in future periods related to the North Platte #2 appraisal well. September 30, 2015 December 31, 2014 ($ in thousands) Cumulative costs: Exploration well costs $ $ Capitalized interest ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Well costs capitalized for a period greater than one year after completion of drilling (included in table above) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2015, capitalized exploration well costs that have been suspended longer than one year are associated with the Company's Shenandoah, North Platte, and Diaman discoveries. These well costs are suspended pending ongoing evaluation including, but not limited to, results of additional appraisal drilling, well-test analysis, additional geological and geophysical data and approval of a development plan. Management believes these discoveries exhibit sufficient indications of hydrocarbons to justify potential development and is actively pursuing efforts to fully assess them. If additional information becomes available that raises substantial doubt as to the economic or operational viability of these discoveries, the associated costs will be expensed at that time. The Heidelberg discovery has been sanctioned for development and the Heidelberg capitalized exploration and appraisal well costs were reclassified to development costs in 2013.

Other Assets

Other Assets	9 Months Ended
	Sep. 30, 2015
Other Assets
Other Assets	8. Other Assets As of September 30, 2015 and December 31, 2014, the balance in other assets consisted of the following: September 30, 2015 December 31, 2014 (in thousands) Debt issue cost(1) $ $ Rig costs(2) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) As of September 30, 2015, the $37.7 million in debt issue costs was related to the issuance of the Company's 2.625% convertible senior notes due 2019 and the Company's 3.125% convertible senior notes due 2024 and the Borrowing Base Facility Agreement, as described in Note 9. As of December 31, 2014, the $36.7 million in debt issue costs included $18.5 million and $18.2 million in costs related to the issuance of the Company's 2.625% convertible senior notes due 2019 and the Company's 3.125% convertible senior notes due 2024, respectively, as described in Note 9. These debt issue costs are amortized over the life of the notes. (2) As of September 30, 2015 and December 31, 2014, the $24.3 million and $12.3 million, respectively, relate to costs associated with the Rowan Reliance drilling rig which is currently drilling in U.S. Gulf of Mexico. These costs are capitalized to the wells over the term of the respective drilling rig contracts.

Long-term Debt

Long-term Debt	9 Months Ended
	Sep. 30, 2015
Long-term Debt
Long-term Debt	9. Long-term Debt As of September 30, 2015, the Company's long-term debt consists of the Borrowing Base Facility Agreement (the "Facility Agreement") entered into on May 29, 2015, the 2.625% convertible senior notes due 2019 issued on December 17, 2012 (the "2.625% Notes"), and the 3.125% convertible senior notes due 2024 issued on May 13, 2014 (the "3.125% Notes", and, collectively with the 2.625% Notes, the "Notes"), as follows: Borrowing Base Facility Agreement On May 29, 2015, Cobalt GOM #1 LLC ("GOM#1"), an indirect, wholly-owned subsidiary of the Company entered into a Borrowing Base Facility Agreement (the "Facility Agreement") with Société Générale, as administrative agent, and certain other lenders. GOM#1 is the direct owner of the oil and gas leases, wells, production facilities and other assets and agreements associated with the Company's Heidelberg development. GOM#1 does not own any of the Company's other oil and gas assets. The Facility Agreement provides for a limited recourse $150 million senior secured reserve-based term loan facility. The proceeds of the loans under the Facility Agreement will be available to fund the majority of GOM#1's share of the remaining Heidelberg field development costs, subject to the maintenance of a debt to equity ratio of the total investment in the Heidelberg development of no more than 70:30. GOM#1 may request that the commitments under the Facility Agreement be increased by up to an additional $100 million upon the satisfaction of certain conditions set forth in the Facility Agreement, and such increase is subject to lender participation. In addition, GOM#1 may request a further commitment increase by up to $400 million if GOM#1's interest in the Heidelberg field is increased, with such commitment increase subject to lender participation. The Company is a party to the Facility Agreement and has limited funding obligations thereunder. Until completion of the Heidelberg development in accordance with the current field development plan and certain other requirements set forth in the Facility Agreement ("Completion"), the Company has guaranteed to fund cost overruns that may be incurred up to an aggregate of $38.7 million. The Company agreed to cash collateralize 50% of its funding obligation in respect of cost overruns by depositing $19.4 million in a collateral account to be established pursuant to the terms of the Facility Agreement. As of September 30, 2015 this amount has not been funded. The amount available for borrowing at any one time under the Facility Agreement is limited to a borrowing base amount determined twice a year using agreed projections by applying the lower of (i) a project life coverage ratio of 1.5:1.0 to the sum of discounted projected net revenues from the Heidelberg field and certain capital expenditures and (ii) a loan life coverage ratio of 1.3:1.0 to the sum of discounted projected net revenues from the Heidelberg field and certain capital expenditures. Interim borrowing base redeterminations can take place between scheduled redetermination dates in limited circumstances specified in the Facility Agreement. Loans made under the Facility Agreement are scheduled to amortize in the manner set forth in the Facility Agreement commencing in July 2018 and will mature on the earlier of (a) May 29, 2020 and (b) the last day of the quarter immediately preceding the first quarter in which the aggregate remaining reserves for the Heidelberg field are projected to be less than 20% of the initial approved reserves. In addition, on or before each redetermination, GOM#1 is required to repay such amount of the loans as is required to reduce the aggregate amount of the loans to the borrowing base amount applicable on the day after such redetermination. After Completion, loans are also subject to mandatory prepayment with 33% of GOM#1's excess cash flow. The Facility Agreement and certain related hedging obligations, if any, are secured by a first priority security interest in substantially all of the assets of GOM#1 (which are comprised only of the oil and gas leases, wells, production facilities and other assets associated with the Heidelberg development), including a mortgage on GOM#1's ownership interest in the Heidelberg field, a pledge of the equity interests of GOM#1 and a pledge of certain intercompany receivables held by the Company. All of GOM#1's revenues from the Heidelberg development will be deposited in collateral accounts established pursuant to the Facility Agreement and applied in accordance with a cash waterfall in the manner specified in the Facility Agreement. GOM#1 is required to maintain a debt service reserve account for the benefit of the lenders under the Facility Agreement, which must remain funded at all times to the level specified in the Facility Agreement. At GOM#1's election, interest for borrowings under the Facility Agreement are determined by reference to (a) the London interbank offered rate, or LIBOR, plus an applicable margin of (i) 6.00% per annum prior to Completion and (ii) 4.00% following Completion or (b) a base rate plus an applicable margin of (i) 5.00% prior to Completion and (ii) 3.00% following Completion. Prior to Completion, GOM#1 is also required to pay a commitment fee equal to 40% of the applicable margin payable on the unused commitments under the Facility Agreement. Interest on base rate loans and the commitment fee are generally payable quarterly. Interest on LIBOR loans are generally payable at the end of the applicable interest period but no less frequently than quarterly. The Facility Agreement contains various covenants that limit, among other things, GOM#1's ability to incur indebtedness, grant liens on its assets, merge or consolidate with other entities, sell its assets, make loans, acquisitions, capital expenditures and other investments, abandon or decommission the Heidelberg field, modify material agreements relating thereto, enter into commodity hedges and pay dividends and distributions to its parent entities. The Facility Agreement includes customary events of default for transactions of this type, including events of default relating to non-payment of principal, interest or fees, inaccuracy of representations and warranties, violation of covenants, cross-defaults, bankruptcy and insolvency events, certain unsatisfied judgments, loan documents not being valid, defaults under project documents that are not replaced, change in control, expropriation, abandonment or decommissioning of the Heidelberg field, material title defects, the failure to pay cost overruns when due and the failure to reach Completion on or before May 29, 2018. In addition, the Facility Agreement provides that an event of default will occur if (a) the debt to equity ratio exceeds 70:30 or (b) the then current projections show that (i) the project loan life coverage ratio in any calculation period will be 1.5:1.0 or less, (ii) the loan life coverage ratio in any calculation period will be 1.3:1.0 or less or (iii) the debt service coverage ratio in any calculation period will be 1.2:1.0 or less. If an event of default occurs, the lenders will be able to accelerate the maturity of the Facility Agreement and exercise other rights and remedies. As of September 30, 2015, the Company has not borrowed any amounts under the Facility Agreement. 2.625% Convertible Senior Notes due 2019 On December 17, 2012, the Company issued $1.38 billion aggregate principal amount of the 2.625% Notes. The 2.625% Notes are the Company's senior unsecured obligations and interest is payable semi-annually in arrears on June 1 and December 1 of each year. The 2.625% Notes will mature on December 1, 2019, unless earlier repurchased or converted in accordance with the terms of the 2.625% Notes. The 2.625% Notes may be converted at the option of the holder at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date, in multiples of $1,000 principal amount. The 2.625% Notes are convertible at an initial conversion rate of 28.023 shares of common stock per $1,000 principal amount, representing an initial conversion price of approximately $35.68 per share for a total of approximately 38.7 million underlying shares. The conversion rate is subject to adjustment upon the occurrence of certain events, as defined in the indenture governing the 2.625% Notes, but will not be adjusted for any accrued and unpaid interest except in limited circumstances. Upon conversion, the Company's conversion obligation may be satisfied, at the Company's option, in cash, shares of common stock or a combination of cash and shares of common stock. 3.125% Convertible Senior Notes due 2024 On May 13, 2014, the Company issued $1.3 billion aggregate principal amount of the 3.125% Notes. The 3.125% Notes are the Company's senior unsecured obligations and rank equal in right of payment to the 2.625% Notes. Interest on the 3.125% Notes is payable semi-annually in arrears on May 15 and November 15 of each year. The 3.125% Notes will mature on May 15, 2024, unless earlier repurchased, converted or redeemed in accordance with the terms of the Notes. Prior to November 15, 2023, the 3.125% Notes are convertible only under the following circumstances: (1) during any fiscal quarter commencing after March 31, 2015 (and only during such fiscal quarter), if the last reported sale price of the Company's common stock for at least 20 trading days (whether or not consecutive) during a 30 consecutive trading-day period ending on, and including, the last trading day of the immediately preceding fiscal quarter exceeds $30.00 on each applicable trading day; (2) during the five business-day period after any five consecutive trading-day period (the "3.125% Notes Measurement Period") in which the trading price per $1,000 principal amount of notes for each trading day of the 3.125% Notes Measurement Period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such trading day; (3) if the Company calls all or any portion of the 3.125% Notes for redemption, at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the related redemption date; or (4) upon the occurrence of specified distributions or the occurrence of specified corporate events. On or after November 15, 2023, the 3.125% Notes may be converted at the option of the holder at any time prior to 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the stated maturity date, in multiples of $1,000 principal amount. As of September 30, 2015, none of the conditions allowing holders of the 3.125% Notes to convert had been met. The 3.125% Notes are convertible at an initial conversion rate of 43.3604 shares of common stock per $1,000 principal amount, representing an initial conversion price of approximately $23.06 per share for a total of approximately 56.4 million underlying shares. The conversion rate is subject to adjustment upon the occurrence of certain events, as defined in the indenture governing the 3.125% Notes, but will not be adjusted for any accrued and unpaid interest except in limited circumstances. Upon conversion, the Company's conversion obligation may be satisfied, at the Company's option, in cash, shares of common stock or a combination of cash and shares of common stock. Holders of the Notes who convert their Notes in connection with a "make- whole fundamental change", as defined in the indenture governing these Notes, may be entitled to a make-whole premium in the form of an increase in the conversion rate. Additionally, in the event of a fundamental change, as defined in the indenture governing the Notes, holders of the Notes may require the Company to repurchase for cash all or a portion of their Notes equal to $1,000 or a multiple of $1,000 at a fundamental change repurchase price equal to 100% of the principal amount of Notes, plus accrued and unpaid interest, if any, to, but not including, the fundamental change repurchase date. Upon the occurrence of an Event of Default, as defined within the indenture governing the Notes, the trustee or the holders of at least 25% in aggregate principal amount of the Notes then outstanding may declare 100% of the principal of, and accrued and unpaid interest on, all the Notes to be due and payable immediately In accordance with accounting guidance relating to, " Debt with Conversion and Other Options ", the Company separately accounts for the liability and equity conversion components of the Notes due to the Company's option to settle the conversion obligation in cash. The fair value of the Notes excluding the conversion feature at the date of issuance was calculated based on the fair value of similar non-convertible debt instruments. The resulting value of the conversion option of the Notes was recognized as a debt discount and recorded as additional paid-in capital on the Company's consolidated balance sheets. Total debt issue cost on the Notes was allocated to the liability component and to the equity component of the Notes accordingly. The debt discount and the liability component of the debt issue costs are amortized over the term of the Notes. The effective interest rate used to amortize the debt discount and the liability component of the debt issue costs were approximately 8.40% and 8.97% on the 2.625% Notes and the 3.125% Notes, respectively, based on the Company's estimated non-convertible borrowing rate as of the date the Notes were issued. Since the Company incurred losses for all periods, the impact of the conversion option would be anti-dilutive to the earnings per share and therefore was not included in the calculation. The carrying amounts of the liability components of the Notes were as follows: September 30, 2015 December 31, 2014 Principal Amount Unamortized discount(1) Carrying Amount Principal Amount Unamortized discount Carrying Amount ($ in thousands) Carrying amount of liability component 2.625% Notes $ $ ) $ $ $ ) $ 3.125% Notes ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Unamortized discount will be amortized over the remaining life of the Notes which is 4.25 years for the 2.625% Notes and 8.75 years for the 3.125% Notes. The carrying amounts of the equity components of the Notes were as follows: September 30, 2015 December 31, 2014 ($ in thousands) Debt discount relating to value of conversion option $ $ Debt issue costs ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value The fair value of the Notes excluding the conversion feature was calculated based on the fair value of similar non-convertible debt instruments since an observable quoted price of the Notes or a similar asset or liability is not readily available. As of September 30, 2015 and December 31, 2014, the fair values of the Notes were as follows: September 30, 2015 December 31, 2014 ($ in thousands) 2.625% Notes $ $ 3.125% Notes ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2015, the Company had $27.3 million accrued for interest on the Notes and commitment fees associated with the Facility Agreement. For the three months ended September 30, 2015 and 2014, the interest expense, net of capitalized amount, relating to the Notes and certain costs and commitment fees associated with the Facility Agreement was $14.7 million and $23.5 million, respectively. For the nine months ended September 30, 2015 and 2014, the interest expense, net of capitalized amount, relating to the Notes was $52.6 million and $52.6 million, respectively. As of September 30, 2015 and December 31, 2014, the debt discounts associated with the 2.625% Notes and the 3.125% Notes resulted in the recognition of $241.8 million and $264.3 million of deferred tax liability, respectively. The Company is in an overall net deferred tax asset position with a full valuation allowance. Therefore, the Company has determined that it is more likely than not that all of the deferred tax assets will not be realized.

Angola Transaction

Angola Transaction	9 Months Ended
	Sep. 30, 2015
Angola Transaction
Angola Transaction	10. Angola Transaction On August 22, 2015, Cobalt International Energy Angola Ltd. ("Cobalt Angola"), a wholly-owned subsidiary of the Company, executed a purchase and sale agreement (the "Purchase and Sale Agreement") with Sonangol for the sale by Cobalt Angola to Sonangol of the entire issued and outstanding share capital of CIE Angola Block 20 Ltd. and CIE Angola Block 21 Ltd., which respectively hold the Company's 40% working interest in each of Block 20 and Block 21 offshore Angola for aggregate gross consideration of $1.75 billion before Angolan withholding taxes of approximately $19.7 million (to be netted out of the gross consideration to be paid to Cobalt Angola) and certain other U.S. and Angolan taxes, expenses, and contingent liabilities. Sonangol Pesquisa e Produção, S.A., an affiliate of Sonangol, currently holds a 30% working interest in Block 20 and a 60% working interest in Block 21. The Angola Transaction is subject to Angolan government approvals. The Purchase and Sale Agreement provides for the payment of the net consideration by Sonangol to Cobalt Angola of (i) $250 million within 7 days following the execution of the Purchase and Sale Agreement (the "First Payment"), (ii) approximately $1.28 billion within 15 days following the receipt of the Angolan government approvals (the "Second Payment"), and (iii) $200 million within the earlier of 30 days following the execution of a transfer of operations agreement, which will contain terms and conditions governing the transition of operations on each of Block 20 and Block 21 from the Company to a new operator, or one year from the execution of the Purchase and Sale Agreement (the "Third Payment"). The Purchase and Sale Agreement further provides that within 15 days following the receipt of the Angolan government approvals, Sonangol shall reimburse Cobalt Angola for its share of costs attributable to Block 20 and Block 21 for the period from January 1, 2015 through the date upon which Cobalt Angola receives the Angolan government approvals (the "Reimbursement Amount"). The Company estimates that its share of costs attributable to Block 20 and Block 21 for the period from January 1, 2015 through September 30, 2015 is approximately $307 million, which excludes (i) a cash collateralized letter of credit of approximately $82.5 million related to Block 20 that will be released following the consummation of the Angola Transaction, and (ii) outstanding joint interest and other receivables attributable to Block 20 and Block 21 of approximately $57.9 million. The obligation of Cobalt Angola to transfer the share capital of CIE Angola Block 20 Ltd. and CIE Angola Block 21 Ltd. to Sonangol and consummate the Angola Transaction is subject to the receipt by Cobalt Angola of the First Payment, the Second Payment and the Reimbursement Amount. Following completion of the transfer of the shares of CIE Angola Block 20 Ltd. and CIE Angola Block 21 Ltd., the Company shall relinquish its interest in Block 9 offshore Angola to Sonangol. If the Angolan government approvals are not received within one year from the execution date of the Purchase and Sale Agreement, the Purchase and Sale Agreement will automatically terminate and any obligations executed by the parties thereto shall be restituted in order to put such parties in their original positions as if no agreement had been executed. As a result, the First Payment has been reported as restricted cash on the balance sheet. Pursuant to the Purchase and Sale Agreement, the Company is required to provide certain transition services to Sonangol, which may include continuing to support operations on Block 20 and 21 on a no-profit no-loss basis until Sonangol nominates a new operator or operators of such blocks, despite the fact that the Company may have already transferred the share capital of its subsidiaries holding its working interests in Blocks 20 and 21 to Sonangol. The Company received the First Payment during the quarterly period ended September 30, 2015. The Angola Transaction is currently pending Angola government approval, and the Company therefore has not received the Second Payment, Third Payment or Reimbursement Amount. Royalty Agreement On February 13, 2009 the Company entered into a restated overriding royalty agreement (the "Royalty Agreement") with Whitton Petroleum Services Limited ("Whitton"). Pursuant to the terms of the Royalty Agreement, in consideration for Whitton's consulting services in connection with Blocks 9, 20 and 21 offshore Angola and the Company's business and operations in Angola, Whitton is to receive quarterly payments (measured in U.S. Dollars) equal to 2.5% of the market price of the Company's share of the crude oil produced in such quarter and not used in petroleum operations, less the cost recovery crude oil, assuming the applicable government contract is a production sharing agreement. If the applicable government contract is a risk services agreement and not a production sharing agreement (which is the case with respect to Blocks 9 and 21), pursuant to the Royalty Agreement the Company has undertaken to agree with Whitton an economic model (the "RSA Economic Model") containing terms equivalent to those in such risk services agreement and using actual production and costs. The RSA Economic Model has not yet been agreed with Whitton. Should the Company assign all of its interest in such Blocks, Whitton may, depending on the option the Company elects, have the right to receive the market value of its rights and obligations under the Royalty Agreement, based upon the amount in cash a willing transferee of such rights and obligations would pay a willing transferor in an arm's length transaction. Given potential issues regarding how such market value of Whitton's rights and obligations under the Royalty Agreement could be calculated, including, without limitation, outstanding issues related to the RSA Economic Model, the amount of any such payment that could be owed to Whitton upon completion of the Angola Transaction is uncertain, but may be material. The Company's working interests in Blocks 9, 20, and 21 offshore Angola have been classified as "held for sale" on the consolidated balance sheet. The results of operations associated with Blocks 9, 20 and 21 offshore Angola have been presented as discontinued operations in the accompanying consolidated statement of operations. Historically, the Company's Angolan subsidiaries constituted a significant portion of its West Africa segment. The Company's operations in Gabon have been combined with its United States segment and are reported as one segment. The following table summarizes the assets and liabilities associated with Blocks 9, 20, and 21 offshore Angola: September 30, 2015 December 31, 2014(1) ($ in thousands) Cash and cash equivalents $ $ Joint interest and other receivables Prepaid expenses and other current assets Inventory Short term restricted funds Oil and gas properties Other property and equipment, net Long term restricted funds Other assets ​ ​ ​ ​ ​ ​ ​ ​ Total assets of the discontinued operation ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade and other accounts payable ) ) Accrued liabilities ) ) Short term contractual obligations ) ) Long term contractual obligations ) ) Other long term liabilities — ) ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities of the discontinued operation $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amounts in the comparative period are broken out between current and long-term on the consolidated balance sheet. Results for Blocks 9, 20, and 21 offshore Angola classified within discontinued operations consisted of the following: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Seismic and exploration $ $ $ $ Dry hole expense and impairment General and administrative Depreciation and amortization ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Seismic and Exploration Expense

Seismic and Exploration Expenses	9 Months Ended
	Sep. 30, 2015
Seismic and Exploration Expenses
Seismic and Exploration Expenses	11. Seismic and Exploration Expenses Seismic and exploration expenses consisted of the following: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Seismic costs $ $ $ $ Leasehold delay rentals Other exploration expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Equity Based Compensation

Equity Based Compensation	9 Months Ended
	Sep. 30, 2015
Equity Based Compensation
Equity Based Compensation	12. Equity Based Compensation The Company accounts for stock-based compensation at fair value. The Company grants various types of stock-based awards including stock options, restricted stock and performance-based awards. The fair value of stock option awards is determined using the Black-Scholes-Merton option-pricing model. For restricted stock awards with market conditions, the fair value of the awards is measured using the Monte Carlo pricing model. Restricted stock awards without market conditions are valued using the market price of the Company's common stock on the grant date. The Company records compensation cost, net of estimated forfeitures, for stock-based compensation awards over the requisite service period except for performance-based awards, which are amortized on a straight-line basis over a weighted average period. During the nine months ended September 30, 2015, the Company granted a total of 3,503,948 shares of restricted stock and 746,268 stock options to employees which include 379,746 shares of restricted stock and 746,268 stock options with both service and market conditions granted to three senior officers under the terms of their employment agreements. During the nine months ended September 30, 2015, the Company granted 35,814 shares of common stock as retainer awards and 105,846 restricted stock units to its non-employee directors. The Company recorded equity based compensation expense, net of forfeitures, of $6.5 million and $7.8 million for the three months ended September 30, 2015 and 2014, respectively, and $19.7 million and $23.1 million for the nine months ended September 30, 2015 and 2014, respectively. On February 20, 2015, the Company issued a total of 1,526,835 share appreciation rights ("SARs") under the Company's Long Term Incentive Plan (the "Plan") to the Company's officers, based on the common stock market price at the time of issuance of $8.87 per share. The SARs will vest with respect to one-third (1/3) of the underlying shares on each anniversary of the grant date over the next three years and may be settled, at the Company's discretion, by issuance of the Company's shares or by cash or by a combination of the Company's shares and cash based on the fair market value of the shares on date of exercise. The fair value of a SAR is determined using the Black-Scholes-Merton option-pricing model which at the date of grant was $4.53 per SAR share. The Company accounts for the SAR awards as compensation cost and records a corresponding liability based on the fair value of the SARs at the end of each reporting period. As of September 30, 2015, the fair value of each SAR decreased to $3.52, resulting in a reduction of the fair value of $0.8 million. For the three months and nine months ended September 30, 2015, the Company recognized $0.2 and $1.0 million, respectively, in compensation expense relating to the SAR awards. On April 30, 2015, the Company's stockholders approved the Company's 2015 Long Term Incentive Plan (the "2015 Plan"). The total number of shares of the Company's common stock available for issuance under the 2015 Plan is 12,000,000. The 2015 Plan provides for grants of stock options, stock appreciation rights, restricted stock, restricted stock units, performance awards and other stock-based awards. As of September 30, 2015, the Company has awarded 150,000 shares under the 2015 Plan.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2015
Contingencies
Contingencies	13. Contingencies The Company is currently, and from time to time may be, subject to various lawsuits, claims and proceedings that arise in the normal course of business, including employment, commercial, environmental, safety and health matters. It is not presently possible to determine whether any such matters will have a material adverse effect on the Company's consolidated financial position, results of operations, or liquidity.

Other Matters

Other Matters	9 Months Ended
	Sep. 30, 2015
Other Matters
Other Matters	14. Other Matters As previously disclosed, in November 2011 a formal order of investigation was issued by the SEC related to the Company's operations in Angola. In August 2014, the Company received a Wells Notice from the SEC related to this investigation. In January 2015, the Company received a termination letter from the SEC advising that the SEC's FCPA investigation has concluded and the Staff does not intend to recommend any enforcement action by the SEC. This letter formally concluded the SEC's investigation. The Company continues to cooperate with the Department of Justice ("DOJ") with regard to its ongoing parallel investigation. The Company is unable to predict the outcome of the DOJ's ongoing investigation or any action that the DOJ may decide to pursue.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements include the financial statements of Cobalt International Energy, Inc. and all of its wholly-owned subsidiaries. All significant intercompany transactions and amounts have been eliminated for all periods presented. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles ("GAAP") for interim financial information and the appropriate rules and regulations of the Securities and Exchange Commission ("SEC"). Accordingly, the condensed consolidated financial statements do not include all of the information and footnote disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for interim periods are not necessarily indicative of the results that may be presented for the entire year. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2014.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In April 2015, the FASB amended Accounting Standard Codification Subtopic No. 835-30, Interest—Imputation of Interest (the "ASC Subtopic 835-30"). The amendments require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments. The amendments under ASC Subtopic 835-30 are effective for financial statements issued for fiscal years beginning after December 15, 2015 and interim periods within those fiscal years. However, early adoption is permitted for financial statements that have not been previously issued. The Company expects to comply with the amendments to ASC Subtopic 835-30 for the financial statements at its effective date beginning after December 15, 2015. We do not expect the adoption of ASC 835-30 to have a material impact on the Company's financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates made by the Company include (i) accruals related to expenses, (ii) assumptions used in estimating fair value of equity based awards and the fair value of the liability component of the convertible senior notes and (iii) assumptions used in impairment testing. Although the Company believes these estimates are reasonable, actual results could differ from these estimates.
Investments	Investments The Company's policy on accounting for its investments, which consist entirely of debt securities, is based on the accounting guidance relating to " Accounting for Certain Investments in Debt and Equity Securities ." The Company considers all highly liquid interest-earning investments with a maturity of three months or less at the date of purchase to be cash equivalents. Investments with original maturities of greater than three months and remaining maturities of less than one year are classified as short-term investments. Investments with maturities beyond one year are classified as long-term investments. The debt securities are carried at amortized cost, which approximates fair market value as of September 30, 2015 and December 31, 2014 and are classified as held-to-maturity as the Company has the positive intent and ability to hold them until they mature. The net carrying value of held-to-maturity securities is adjusted for amortization of premiums and accretion of discounts to maturity over the life of the securities. Income related to these securities is reported as a component of interest income in the Company's condensed consolidated statement of operations. See Note 5—Investments . Investments are considered to be impaired when a decline in fair value is determined to be other-than-temporary. The Company conducts a regular assessment of its debt securities with unrealized losses to determine whether securities have other-than-temporary impairment ("OTTI"). This assessment considers, among other factors, the nature of the securities, credit rating or financial condition of the issuer, the extent and duration of the unrealized loss, market conditions and whether the Company intends to sell or whether it is more likely than not that the Company will be required to sell the debt securities. As of September 30, 2015 and December 31, 2014, the Company has no OTTI in its debt securities.
Asset Retirement Obligation	Asset Retirement Obligation The Company expects to have significant obligations under its lease agreements and federal regulation to remove its equipment and restore land or seabed at the end of oil and natural gas production operations. These asset retirement obligations ("ARO") are primarily associated with plugging and abandoning wells and removing and disposing of offshore oil and natural gas platforms. Estimating the future restoration and removal cost is difficult and requires the Company to make estimates and judgments because most of the removal obligations are many years in the future and contracts and regulation often have vague descriptions of what constitutes removal. Asset removal technologies and cost are constantly changing, as are regulatory, political, environmental, safety and public relations considerations. Pursuant to the accounting guidance relating to " Assets Retirement Obligations ", the Company is required to record a separate liability for the discounted present value of its asset retirement obligations, with an offsetting increase to the related oil and natural gas properties representing asset retirement costs on the balance sheet. The cost of the related oil and natural gas asset, including the asset retirement cost, is depreciated over the useful life of the asset. The asset retirement obligation is recorded at its estimated fair value, measured by reference to the expected future cash outflows required to satisfy the retirement obligation discounted at the Company's credit-adjusted risk-free interest rate. Accretion expense is recognized over time as the discounted liability is accreted to its expected settlement value. Inherent to the present value calculation are numerous estimates, assumptions and judgments, including the ultimate settlement amounts, inflation factors, credit adjusted risk-free rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. To the extent future revisions to these assumptions impact the present value of the abandonment liability, the Company will make corresponding adjustments to both the asset retirement obligation and the related oil and natural gas property asset balance. Increases in the discounted abandonment liability resulting from the passage of time will be reflected as additional accretion expense in the consolidated statement of operations. During the quarterly period ended September 30, 2015, the Company recognized a retirement obligation for its Heidelberg field. The following summarizes the changes in the asset retirement obligation for the nine months ended September 30, 2015: September 30, 2015 ($ in thousands) Beginning of period — Liabilities incurred Accretion — ​ ​ ​ ​ ​ End of period $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Capitalized Interest	Capitalized Interest For exploration and development projects that have not commenced production, interest is capitalized as part of the historical cost of developing and constructing assets. Capitalized interest is determined by multiplying the Company's weighted-average borrowing cost on debt by the average amount of qualifying costs incurred. Once an asset subject to interest capitalization is completed and placed in service, the associated capitalized interest is expensed through depreciation or impairment. See Note 7—Property, Plant, and Equipment and Note 9—Long-term Debt .
Earnings (Loss) Per Share	Earnings (Loss) Per Share Basic income (loss) per share was calculated by dividing net income or loss applicable to common shares by the weighted average number of common shares outstanding during the periods presented. The calculation of diluted income (loss) per share includes the potential dilutive impact of non-vested restricted stock, non-vested restricted stock units, outstanding stock options, the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024 during the period, unless their effect is anti-dilutive. For the three months and nine months ended September 30, 2015, 9,861,834 shares of non-vested restricted stock, non-vested restricted stock units, outstanding stock options, the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024, were excluded from the diluted income (loss) per share calculation because they were anti-dilutive. For the three months and nine months ended September 30, 2014, 8,643,212 shares of non-vested restricted stock, non-vested restricted stock units, outstanding stock options and the 2.625% convertible senior notes due 2019 and the 3.125% convertible senior notes due 2024, were excluded from the diluted income (loss) per share because they are anti-dilutive.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2015
Summary of Significant Accounting Policies
Schedule of changes in asset retirement obligation	September 30, 2015 ($ in thousands) Beginning of period — Liabilities incurred Accretion — ​ ​ ​ ​ ​ End of period $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	9 Months Ended
	Sep. 30, 2015
Cash and Cash Equivalents.
Cash and cash equivalents	September 30, 2015 December 31, 2014 ($ in thousands) Cash at banks $ $ Money market funds Held-to-maturity securities(1) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) These securities mature three months or less from the date of purchase.

Restricted Cash and Cash Equi24

Restricted Cash and Cash Equivalents (Tables)	9 Months Ended
	Sep. 30, 2015
Restricted Cash and Cash Equivalents
Schedule of restricted funds	September 30, 2015 December 31, 2014 ($ in thousands) Angolan sale proceeds $ — American Express Bank pledge agreement — Citibank commercial card agreement — ​ ​ ​ ​ ​ ​ ​ ​ Total restricted funds(1) $ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Pursuant to the purchase and sale agreement governing the Angola Transaction, the Company received the First Payment of $250 million during the quarterly period ended September 30, 2015. See Note 10—Angola Transaction . These funds are contractually restricted by the purchase and sale agreement pending the closing of the Angola Transaction. In addition, as of September 30, 2015, approximately $3.0 million was held in collateral accounts established to pledge funds for security of obligations under the American Express Bank Pledge Agreement and the Citibank Commercial Card Agreement. As of September 30, 2015, the Angolan sales proceeds and collateral in these accounts were invested in cash, certificates of deposit, commercial paper, and money market funds, resulting in a net carrying value of approximately $253.0 million. The contractual maturities of these securities are within ninety days.

Joint Interest and Other Rece25

Joint Interest and Other Receivables (Tables)	9 Months Ended
	Sep. 30, 2015
Joint Interest and Other Receivables
Schedule of joint interest and other receivables	September 30, 2015 December 31, 2014 ($ in thousands) Partners in the U.S. Gulf of Mexico $ $ Accrued interest on investment securities Other ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2015
Investments
Schedule of fair value of held-to-maturity securities recorded at amortized cost	September 30, 2015 December 31, 2014 ($ in thousands) Corporate securities $ $ Commercial paper U.S. Agency securities Certificates of deposit ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of held-to-maturity securities included in the company's condensed consolidated balance sheet	September 30, 2015 December 31, 2014 ($ in thousands) Cash and cash equivalents $ $ Short-term investments Restricted cash and cash equivalents — Long-term investments — ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of contractual maturities of held-to-maturity securities	September 30, 2015 December 31, 2014 Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value ($ in thousands) Within 1 year $ $ $ $ After 1 year — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Measurements
Significant financial instruments measured on a recurring basis as categorized by the fair value measurement hierarchy	Level 1 Level 2 Carrying Value Fair Value(1) Carrying Value Fair Value(1) Balance as of September 30, 2015 ($ in thousands) Cash and cash equivalents: Cash $ $ $ — $ — $ Money market funds — — Commercial paper — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted cash and cash equivalents: Money market funds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-term investments: U.S. Agency securities — — Corporate bonds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term investments: Corporate bonds — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — — — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 1 Level 2 Carrying Value Fair Value(1) Carrying Value Fair Value(1) Balance as of December 31, 2014 ($ in thousands) Cash and cash equivalents: Cash $ $ $ — $ — $ Money market funds — — Commercial paper — — Corporate bonds ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short-term investments: U.S. Agency securities — — Corporate bonds — — Commercial paper — — Certificates of deposit — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term investments: Corporate bonds — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Subtotal — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) As of September 30, 2015 and December 31, 2014, the Company did not record any OTTI on these assets.

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	9 Months Ended
	Sep. 30, 2015
Property, Plant, and Equipment
Schedule of property, plant, and equipment	Estimated Useful Life (Years) September 30, 2015 December 31, 2014 ($ in thousands) Oil and Gas Properties: Proved properties: Well and development costs $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total proved properties ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unproved properties: Oil and gas leasehold Less: accumulated valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Exploration wells in process ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total unproved properties ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total oil and gas properties, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Property and Equipment: Computer equipment and software 3 Office equipment and furniture 3 - 5 Leasehold improvements 3 - 10 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less: accumulated depreciation and amortization ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total other property and equipment, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Property, plant, and equipment, net $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of unproved property acquisition costs, net of valuation allowance	September 30, 2015 December 31, 2014 ($ in thousands) Individual oil and gas leaseholds with carrying value greater than $1 million $ $ Individual oil and gas leaseholds with carrying value less than $1 million ​ ​ ​ ​ ​ ​ ​ ​ Accumulated valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total oil and gas leasehold ​ ​ ​ ​ ​ ​ ​ ​
Schedule of net changes in capitalized exploration well costs	September 30, 2015 December 31, 2014 ($ in thousands) Beginning of period $ $ Additions to capitalized exploration Exploration well costs Capitalized interest Reclassifications to wells, facilities, and equipment based on determination of proved reserves — — Amounts charged to expense(1) ) ) ​ ​ ​ ​ ​ ​ ​ ​ End of period $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) The amount of $29.5 million charged to expense for the nine months ended September 30, 2015 primarily represents impairment charges of approximately $22.3 million related to the North Platte #2 appraisal well and impairment charges of approximately $6.6 million related to the lowest portion of the Shenandoah #4 appraisal well. The North Platte #2 appraisal well was plugged and abandoned due to a seal failure in the riser connection system. The well was at a depth of 20,701 feet when the problem with the riser was detected. The Company is continuing to assess what additional impairment charges or other liabilities, including any environmental liabilities, might be incurred in future periods related to the North Platte #2 appraisal well.
Schedule of cumulative costs of capitalized exploration well costs	September 30, 2015 December 31, 2014 ($ in thousands) Cumulative costs: Exploration well costs $ $ Capitalized interest ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Well costs capitalized for a period greater than one year after completion of drilling (included in table above) $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Other Assets (Tables)

Other Assets (Tables)	9 Months Ended
	Sep. 30, 2015
Other Assets
Schedule of other assets	September 30, 2015 December 31, 2014 (in thousands) Debt issue cost(1) $ $ Rig costs(2) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) As of September 30, 2015, the $37.7 million in debt issue costs was related to the issuance of the Company's 2.625% convertible senior notes due 2019 and the Company's 3.125% convertible senior notes due 2024 and the Borrowing Base Facility Agreement, as described in Note 9. As of December 31, 2014, the $36.7 million in debt issue costs included $18.5 million and $18.2 million in costs related to the issuance of the Company's 2.625% convertible senior notes due 2019 and the Company's 3.125% convertible senior notes due 2024, respectively, as described in Note 9. These debt issue costs are amortized over the life of the notes. (2) As of September 30, 2015 and December 31, 2014, the $24.3 million and $12.3 million, respectively, relate to costs associated with the Rowan Reliance drilling rig which is currently drilling in U.S. Gulf of Mexico. These costs are capitalized to the wells over the term of the respective drilling rig contracts.

Long-term Debt (Tables)

Long-term Debt (Tables)	9 Months Ended
	Sep. 30, 2015
Long-term Debt
Schedule of the carrying amounts of the liability components of the Notes	September 30, 2015 December 31, 2014 Principal Amount Unamortized discount(1) Carrying Amount Principal Amount Unamortized discount Carrying Amount ($ in thousands) Carrying amount of liability component 2.625% Notes $ $ ) $ $ $ ) $ 3.125% Notes ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ) $ $ $ ) $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Unamortized discount will be amortized over the remaining life of the Notes which is 4.25 years for the 2.625% Notes and 8.75 years for the 3.125% Notes.
Schedule of carrying amounts of the equity components of the Notes	September 30, 2015 December 31, 2014 ($ in thousands) Debt discount relating to value of conversion option $ $ Debt issue costs ) ) ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of the fair value of the Notes excluding the conversion feature	September 30, 2015 December 31, 2014 ($ in thousands) 2.625% Notes $ $ 3.125% Notes ​ ​ ​ ​ ​ ​ ​ ​ Total $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Angola Transaction (Tables)

Angola Transaction (Tables)	9 Months Ended
	Sep. 30, 2015
Angola Transaction
Summary of assets and liabilities and operation results associated with Blocks 9, 20, and 21 offshore Angola	The following table summarizes the assets and liabilities associated with Blocks 9, 20, and 21 offshore Angola: September 30, 2015 December 31, 2014(1) ($ in thousands) Cash and cash equivalents $ $ Joint interest and other receivables Prepaid expenses and other current assets Inventory Short term restricted funds Oil and gas properties Other property and equipment, net Long term restricted funds Other assets ​ ​ ​ ​ ​ ​ ​ ​ Total assets of the discontinued operation ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Trade and other accounts payable ) ) Accrued liabilities ) ) Short term contractual obligations ) ) Long term contractual obligations ) ) Other long term liabilities — ) ​ ​ ​ ​ ​ ​ ​ ​ Total liabilities of the discontinued operation $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Amounts in the comparative period are broken out between current and long-term on the consolidated balance sheet. Results for Blocks 9, 20, and 21 offshore Angola classified within discontinued operations consisted of the following: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Seismic and exploration $ $ $ $ Dry hole expense and impairment General and administrative Depreciation and amortization ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Seismic and Exploration Expen32

Seismic and Exploration Expenses (Tables)	9 Months Ended
	Sep. 30, 2015
Seismic and Exploration Expenses
Schedule of seismic and exploration expenses	Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 Seismic costs $ $ $ $ Leasehold delay rentals Other exploration expense ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Summary of Significant Accoun33

Summary of Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2015USD ($)shares	Sep. 30, 2014shares	Sep. 30, 2015USD ($)segmentshares	Sep. 30, 2014shares	Aug. 22, 2015	Dec. 31, 2014USD ($)	May. 13, 2014	Dec. 17, 2012
General
Number of reportable segment | segment			1
Investments
OTTI in debt securities	$ 0		$ 0			$ 0
Changes in asset retirement obligation
Liabilities incurred			3,069,000
End of period	$ 3,069,000		$ 3,069,000
Earnings (Loss) Per Share
Shares of non-vested restricted stock, non vested restricted stock units, outstanding stock options and 2.625% convertible senior notes due 2019 and 3.125% convertible senior notes due 2024, excluded from the diluted income (loss) per share calculation | shares	9,861,834	8,643,212	9,861,834	8,643,212
Discontinued operations held for sale | Block 20, offshore Angola | CIE Angola Block 20 Ltd
General
Percentage of working interest acquired					40.00%
Discontinued operations held for sale | Block 21, offshore Angola | CIE Angola Block 21 Ltd
General
Percentage of working interest acquired					40.00%
2.625% convertible senior notes due 2019
Earnings (Loss) Per Share
Interest rate (as a percent)	2.625%		2.625%			2.625%		2.625%
3.125% convertible senior notes due 2024
Earnings (Loss) Per Share
Interest rate (as a percent)	3.125%		3.125%			3.125%	3.125%

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Cash and Cash Equivalents.
Cash at banks	$ 20,957	$ 45,733
Money market funds	55,002	122,218
Held-to-maturity securities	24,488	78,753
Total	$ 100,447	$ 246,704	$ 155,435	$ 165,663

Restricted Cash and Cash Equi35

Restricted Cash and Cash Equivalents (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)
Restricted Cash and Cash Equivalents
Restricted cash and cash equivalents	$ 252,950
Contractual maturity period of restricted cash and cash equivalents	90 days
Angloan sale proceeds
Restricted Cash and Cash Equivalents
Restricted cash and cash equivalents	$ 250,000
Consideration received	250,000
American Express Bank And Citibank pledge agreement
Restricted Cash and Cash Equivalents
Collateral held	3,000
American Express Bank pledge agreement
Restricted Cash and Cash Equivalents
Restricted cash and cash equivalents	750
Citibank, commercial card agreement
Restricted Cash and Cash Equivalents
Restricted cash and cash equivalents	$ 2,200

Joint Interest and Other Rece36

Joint Interest and Other Receivables (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Joint Interest and Other Receivables
Settlement period for bills under operating agreements	30 days
Joint Interest and Other Receivables
Accrued interest on investment securities	$ 4,740	$ 7,663
Other	249	2,637
Receivable attributable to joint interest partners	91,666	13,575
Partners in the U.S. Gulf of Mexico
Joint Interest and Other Receivables
Receivable attributable to joint interest partners	$ 86,677	$ 3,275

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Investments
Fair market value	$ 1,355,716	$ 1,935,006
Held-to-maturities, Carrying value
Within 1 year	1,355,716	1,608,959
After 1 year		326,047
Total	1,355,716	1,935,006
Held-to-maturity securities, Estimated fair value
Within 1 year	1,355,716	1,608,959
After 1 year		326,047
Total	1,355,716	1,935,006
Cash and cash equivalents
Investments
Fair market value	24,488	78,753
Held-to-maturity securities, Estimated fair value
Total	24,488	78,753
Short-term investments
Investments
Fair market value	1,235,350	1,530,206
Held-to-maturity securities, Estimated fair value
Total	1,235,350	1,530,206
Restricted cash and cash equivalents
Investments
Fair market value	95,878
Held-to-maturity securities, Estimated fair value
Total	95,878
Long-term investments
Investments
Fair market value		326,047
Held-to-maturity securities, Estimated fair value
Total		326,047
Corporate securities
Investments
Fair market value	768,016	1,321,261
Held-to-maturity securities, Estimated fair value
Total	768,016	1,321,261
Commercial paper
Investments
Fair market value	491,749	483,534
Held-to-maturity securities, Estimated fair value
Total	491,749	483,534
U.S. Agency Securities
Investments
Fair market value	24,999	24,996
Held-to-maturity securities, Estimated fair value
Total	24,999	24,996
Certificates of deposit
Investments
Fair market value	70,952	105,215
Held-to-maturity securities, Estimated fair value
Total	$ 70,952	$ 105,215

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	$ 100,447	$ 246,704	$ 155,435	$ 165,663
Restricted cash and cash equivalents	252,950
Short-term investments	1,235,350	1,530,206
Long-term investments		326,047
Total	1,588,747	2,102,957
Cash. | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	20,957	45,733
Money market funds | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	55,002	122,218
Restricted cash and cash equivalents	157,702
Commercial paper | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	24,488	70,524
Restricted cash and cash equivalents	95,128
Short-term investments	372,133	413,010
U.S. Agency Securities | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Short-term investments	24,999	24,996
Corporate securities | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents		8,229
Short-term investments	768,016	986,985
Long-term investments		326,047
Certificates of deposit | Recurring basis
Significant financial instruments as categorized by the fair value measurement hierarchy
Restricted cash and cash equivalents	750
Short-term investments	70,202	105,215
Level 1 | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	75,959	167,951
Restricted cash and cash equivalents	157,072
Total	233,031	167,951
Level 1 | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	75,959	167,951
Restricted cash and cash equivalents	157,072
Total	233,031	167,951
Level 1 | Cash. | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	20,957	45,733
Level 1 | Cash. | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	20,957	45,733
Level 1 | Money market funds | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	55,002	122,218
Restricted cash and cash equivalents	157,072
Level 1 | Money market funds | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	55,002	122,218
Restricted cash and cash equivalents	157,072
Level 2 | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	24,488	78,753
Restricted cash and cash equivalents	95,878
Short-term investments	1,235,350	1,530,206
Long-term investments		326,047
Total	1,355,716	1,935,006
Level 2 | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	24,488	78,753
Restricted cash and cash equivalents	95,878
Short-term investments	1,235,350	1,530,206
Long-term investments		326,047
Total	1,355,716	1,935,006
Level 2 | Commercial paper | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	24,488	70,524
Restricted cash and cash equivalents	95,128
Short-term investments	372,133	413,010
Level 2 | Commercial paper | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents	24,488	70,524
Restricted cash and cash equivalents	95,128
Short-term investments	372,133	413,010
Level 2 | U.S. Agency Securities | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Short-term investments	24,999	24,996
Level 2 | U.S. Agency Securities | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Short-term investments	24,999	24,996
Level 2 | Corporate securities | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents		8,229
Short-term investments	768,016	986,985
Long-term investments		326,047
Level 2 | Corporate securities | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Cash and cash equivalents		8,229
Short-term investments	768,016	986,985
Long-term investments		326,047
Level 2 | Certificates of deposit | Recurring basis | Carrying Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Restricted cash and cash equivalents	750
Short-term investments	70,202	105,215
Level 2 | Certificates of deposit | Recurring basis | Fair Value
Significant financial instruments as categorized by the fair value measurement hierarchy
Restricted cash and cash equivalents	750
Short-term investments	$ 70,202	$ 105,215

Property, Plant, and Equipmen39

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015	Dec. 31, 2014
Property, Plant, and Equipment
Well and development costs	$ 318,773		$ 318,773			$ 183,221
Total proved properties	318,773		318,773			183,221
Oil and gas leasehold	404,781		404,781			406,643
Less: accumulated valuation allowance	(180,410)		(180,410)			(208,725)
Total oil and gas leasehold	224,371		224,371			197,918
Total unproved properties	732,600		732,600			528,017
Total oil and gas properties, net	1,051,373		1,051,373			711,238
Other Property and Equipment	8,849		8,849			8,661
Less: accumulated depreciation and amortization	(6,369)		(6,369)			(5,245)
Total other property and equipment	2,480		2,480			3,416
Total property, plant, and equipment, net	1,053,853		1,053,853			714,654
Depreciation and amortization	346	$ 410	1,125	$ 1,277
Percentage of working interest assigned to wholly owned subsidiary					9.375%
Unproved property acquisition costs, net of valuation allowance
Unproved property	404,781		404,781			406,643
Accumulated valuation allowance	(180,410)		(180,410)			(208,725)
Total oil and gas leasehold	224,371		224,371			197,918
Development well costs
Property, Plant, and Equipment
Well and development costs	189,500		189,500			132,100
Exploration wells in process
Property, Plant, and Equipment
Total unproved properties	508,229		508,229			330,099
Exploration wells in process | Exploration well costs
Property, Plant, and Equipment
Well and development costs	129,300		$ 129,300			51,100
Computer equipment and software
Property, Plant, and Equipment
Estimated Useful Life			3 years
Other Property and Equipment	5,349		$ 5,349			5,214
Office equipment and furniture
Property, Plant, and Equipment
Other Property and Equipment	1,349		$ 1,349			1,329
Office equipment and furniture | Minimum
Property, Plant, and Equipment
Estimated Useful Life			3 years
Office equipment and furniture | Maximum
Property, Plant, and Equipment
Estimated Useful Life			5 years
Leasehold improvements
Property, Plant, and Equipment
Other Property and Equipment	2,151		$ 2,151			2,118
Leasehold improvements | Minimum
Property, Plant, and Equipment
Estimated Useful Life			3 years
Leasehold improvements | Maximum
Property, Plant, and Equipment
Estimated Useful Life			10 years
Oil and gas properties, net
Property, Plant, and Equipment
Oil and gas leasehold	404,781		$ 404,781			406,643
Less: accumulated valuation allowance	(180,410)		(180,410)			(208,725)
Unproved property acquisition costs, net of valuation allowance
Individual oil and gas leaseholds with carrying value greater than $1 million	326,250		326,250			322,727
Individual oil and gas leaseholds with carrying value less than $1 million	78,531		78,531			83,916
Unproved property	404,781		404,781			406,643
Accumulated valuation allowance	(180,410)		(180,410)			(208,725)
Upper limit of individual leasehold	1,000		1,000			1,000
Lower limit of individual leasehold	$ 1,000		$ 1,000			$ 1,000

Property, Plant, and Equipmen40

Property, Plant, and Equipment (Details 2) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015USD ($)ft	Dec. 31, 2014USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Capitalized Exploratory Well Costs
Period to determine an exploration well has commercially sufficient quantity of proved reserved	1 year
Net changes in capitalized exploratory well costs (excluding any related leasehold costs)
Beginning of period	$ 330,099	$ 233,143
Amounts charged to expense	(29,454)	(64,253)
End of period	508,229	330,099
Cumulative costs of capitalized exploratory well costs (excluding any related leasehold costs)
Cumulative costs	$ 330,099	233,143	$ 508,229	$ 330,099
Well costs capitalized for a period greater than one year after completion of drilling			247,845	233,141
Number of feet | ft	20,701
Exploration well costs
Net changes in capitalized exploratory well costs (excluding any related leasehold costs)
Beginning of period	$ 315,697
Additions to capitalized exploration	191,777	151,687
End of period	478,019	315,697
Cumulative costs of capitalized exploratory well costs (excluding any related leasehold costs)
Cumulative costs	315,697	315,697	478,019	315,697
Capitalized interest
Net changes in capitalized exploratory well costs (excluding any related leasehold costs)
Beginning of period	14,402
Additions to capitalized exploration	15,807	9,522
End of period	30,210	14,402
Cumulative costs of capitalized exploratory well costs (excluding any related leasehold costs)
Cumulative costs	14,402	$ 14,402	$ 30,210	$ 14,402
North Platte #2 appraisal well
Net changes in capitalized exploratory well costs (excluding any related leasehold costs)
Impairment charges	22,300
Shenandoah #4 appraisal well
Net changes in capitalized exploratory well costs (excluding any related leasehold costs)
Impairment charges	$ 6,600

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2015	May. 13, 2014	Dec. 17, 2012
Other Assets
Debt issue cost	$ 36,708	$ 37,727
Rig costs	12,324	24,318
Other assets	49,032	$ 62,045
2.625% convertible senior notes due 2019
Other Assets
Debt issue costs	$ 18,500
Interest rate (as a percent)	2.625%	2.625%		2.625%
3.125% convertible senior notes due 2024
Other Assets
Debt issue costs	$ 18,200
Interest rate (as a percent)	3.125%	3.125%	3.125%

Long-term Debt (Details)

Long-term Debt (Details) $ / shares in Units, $ in Thousands	May. 29, 2015USD ($)	May. 13, 2014USD ($)item$ / shares	Dec. 17, 2012USD ($)item$ / shares	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)item$ / shares	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)
Debt instrument
Accrued for interest				$ 27,300		$ 27,300	$ 27,300
Carrying amounts of the liability components
Carrying amount of the liability components				1,992,499		$ 1,992,499	1,992,499		$ 1,928,528
Carrying amounts of the equity components
Interest expense, net of capitalized amount				$ 14,700	$ 23,500		$ 52,600	$ 52,600
Facility Agreement
Debt instrument
Maximum guaranteed amount to fund cost overruns	$ 38,700
Cash obligated to deposit in a collateral account for funding of cost overruns	$ 19,400
Funding obligation in cash for cost overruns (as a percent)	50.00%
Project life coverage ratio	1.5
Loan life coverage ratio	1.3
Aggregate remaining reserves for the Heidelberg field to the initial approved reserves (as a percent)	20.00%
Maximum debt to equity ratio	70.00%
Maximum project loan life coverage ratio	1.5
Maximum loan life coverage ratio	1.3
Maximum debt service coverage ratio	1.2
2.625% convertible senior notes due 2019
Debt instrument
Aggregate principal amount of notes issued			$ 1,380,000
Interest rate (as a percent)			2.625%	2.625%		2.625%	2.625%		2.625%
Initial conversion rate of common stock			28.023
Initial conversion price per share of common stock (in dollars per share) | $ / shares			$ 35.68
Number of underlying shares that the holder of the debt instrument would receive upon conversion | item			38,700,000
Effective interest rate used to amortize liability component of debt issue costs (as a percent)			8.40%
Carrying amounts of the liability components
Principal Amount				$ 1,380,000		$ 1,380,000	$ 1,380,000		$ 1,380,000
Unamortized discount				(256,498)		(256,498)	(256,498)		(295,509)
Carrying amount of the liability components				1,123,502		1,123,502	$ 1,123,502		1,084,491
Remaining term of debt							4 years 3 months
Carrying amounts of the equity components
Fair value of the notes excluding conversion feature				$ 1,371,000		$ 1,371,000	$ 1,371,000		$ 1,361,000
3.125% convertible senior notes due 2024
Debt instrument
Aggregate principal amount of notes issued		$ 1,300,000
Interest rate (as a percent)		3.125%		3.125%		3.125%	3.125%		3.125%
Initial conversion rate of common stock		43.3604
Initial conversion price per share of common stock (in dollars per share) | $ / shares		$ 23.06
Number of underlying shares that the holder of the debt instrument would receive upon conversion | item		56,400,000
Number of days within 30 consecutive trading days in which the closing price of the entity's common stock must exceed the conversion price for the notes to be redeemable | item						20
Number of consecutive trading days during which the closing price of the entity's common stock must exceed the conversion price for at least 20 days in order for the notes to be redeemable						30 days
Minimum sale price of common stock to determine eligibility of conversion | $ / shares						$ 30
Number of business days after any five consecutive trading day period during the note measurement period						5 days
Number of consecutive trading days before five consecutive business days during the note measurement period						5 days
Convertibility of debt, trading price of debt test, percentage of closing price of stock used in calculation						98.00%
Effective interest rate used to amortize liability component of debt issue costs (as a percent)		8.97%
Carrying amounts of the liability components
Principal Amount				$ 1,300,000		$ 1,300,000	$ 1,300,000		$ 1,300,000
Unamortized discount				(431,003)		(431,003)	(431,003)		(455,963)
Carrying amount of the liability components				868,997		868,997	$ 868,997		844,037
Remaining term of debt							8 years 9 months
Carrying amounts of the equity components
Fair value of the notes excluding conversion feature				1,146,000		1,146,000	$ 1,146,000		1,047,000
Notes
Debt instrument
Repurchase price as a percentage of principal amount of debt instrument			100.00%
Specified minimum percentage of principal amount, the holders of which may declare all principal, accrued and unpaid interest to be due and payable immediately, upon the occurrence of an Event of Default			25.00%
Percentage of principal amount, which may be declared by holders of a specified principal amount to be due and payable immediately upon occurrence of an Event of Default			100.00%
Deferred tax liability, from debt discount				241,800		241,800	241,800		264,300
Carrying amounts of the liability components
Principal Amount				2,680,000		2,680,000	2,680,000		2,680,000
Unamortized discount				(687,501)		(687,501)	(687,501)		(751,472)
Carrying amount of the liability components				1,992,499		1,992,499	1,992,499		1,928,528
Carrying amounts of the equity components
Debt discount relating to value of conversion option				866,340		866,340	866,340		866,340
Debt issue costs							(20,185)		(20,185)
Total				846,155		846,155	846,155		846,155
Fair value of the notes excluding conversion feature				$ 2,517,000		$ 2,517,000	$ 2,517,000		$ 2,408,000
GOM#1 | Facility Agreement
Debt instrument
Maximum borrowing capacity	$ 150,000
Availability for additional borrowings, upon the satisfaction of certain conditions	100,000
Availability for additional borrowings, if GOM#1?s interest in the Heidelberg field is increased	$ 400,000
GOM#1 | Prior to Completion | Facility Agreement
Debt instrument
Unused commitment fee (as a percent)	40.00%
GOM#1 | Prior to Completion | London Interbank Offered Rate (LIBOR) | Facility Agreement
Debt instrument
Margin to variable interest rate (as a percent)	6.00%
GOM#1 | Prior to Completion | Base Rate | Facility Agreement
Debt instrument
Margin to variable interest rate (as a percent)	5.00%
GOM#1 | Following Completion | Facility Agreement
Debt instrument
Mandatory prepayment with excess cash flow (in percent)	33.00%
GOM#1 | Following Completion | London Interbank Offered Rate (LIBOR) | Facility Agreement
Debt instrument
Margin to variable interest rate (as a percent)	4.00%
GOM#1 | Following Completion | Base Rate | Facility Agreement
Debt instrument
Margin to variable interest rate (as a percent)	3.00%

Angola Transaction (Details)

Angola Transaction (Details) - USD ($) $ in Thousands	Aug. 22, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Feb. 13, 2009
Angola Transaction
Loss from discontinued operations		$ 9,477	$ 75,453	$ 34,051	$ 117,336
Discontinued operations held for sale | Block 9, Block 20 And Block 21, Offshore Angola
Angola Transaction
Cash and cash equivalents		12,037		12,037		$ 12,017
Joint interest and other receivables		57,851		57,851		46,399
Prepaid expenses and other current assets		10,838		10,838		10,655
Inventory		41,908		41,908		59,581
Short term restricted funds		22,538		22,538		45,062
Oil and gas properties		1,497,632		1,497,632		1,209,741
Other property and equipment, net		10,027		10,027		7,965
Long term restricted funds		82,470		82,470		105,051
Other assets		1,258		1,258		4,904
Total assets of the discontinued operation		1,736,559		1,736,559		1,501,375
Trade and other accounts payable		(15,507)		(15,507)		(7,939)
Accrued liabilities		(109,056)		(109,056)		(116,956)
Short term contractual obligations		(114,439)		(114,439)		(50,285)
Long term contractual obligations		(1,381)		(1,381)		(101,945)
Other long term liabilities						(351)
Total liabilities of the discontinued operation		(240,383)		(240,383)		$ (277,476)
Seismic and exploration		3,825	28,463	13,174	41,111
Dry hole expense and impairment		885	37,849	1,496	39,706
General and administrative		4,145	8,497	16,903	34,560
Depreciation and amortization		622	644	2,478	1,959
Loss from discontinued operations		9,477	$ 75,453	34,051	$ 117,336
Quarterly royalty payment, percentage of the market price of Whitton's rights and obligations under the Royalty Agreement							2.50%
Discontinued operations held for sale | Block 20 and Block 21
Angola Transaction
Maximum time period for obtaining approvals from the Angolan government	1 year
Discontinued operations held for sale | Block 20 and Block 21 | CIE Angola block 20 and block 21
Angola Transaction
Consideration	$ 1,750,000
Withholding taxes for the gross consideration to be paid	19,700
Share of costs attributable to the drilling blocks, net of cash collateralized letter of credit and outstanding joint interest and other receivables		307,000		307,000
Cash collateralized letter of credit		82,500		82,500
Joint interest and other receivables		$ 57,900		$ 57,900
Discontinued operations held for sale | Block 20 and Block 21 | CIE Angola block 20 and block 21 | First Payment
Angola Transaction
Consideration	$ 250,000
Payment period after execution of the Purchase and Sale Agreement	7 days
Discontinued operations held for sale | Block 20 and Block 21 | CIE Angola block 20 and block 21 | Second Payment
Angola Transaction
Consideration	$ 1,280,000
Payment period after receipt of the Angolan government approvals	15 days
Discontinued operations held for sale | Block 20 and Block 21 | CIE Angola block 20 and block 21 | Third Payment
Angola Transaction
Consideration	$ 200,000
Payment period after execution of the Purchase and Sale Agreement	1 year
Payment period after execution of transfer of operations agreement	30 days
Maximum time period for obtaining approvals from the Angolan government to share costs	15 days
Discontinued operations held for sale | Block 20, offshore Angola | CIE Angola Block 20 Ltd
Angola Transaction
Percentage of working interest acquired	40.00%
Discontinued operations held for sale | Block 21, offshore Angola | CIE Angola Block 21 Ltd
Angola Transaction
Percentage of working interest acquired	40.00%
Sonangol Pesquisa e Producao, S.A | Block 20, offshore Angola | CIE Angola Block 20 Ltd
Angola Transaction
Percentage of working interest acquired	30.00%
Sonangol Pesquisa e Producao, S.A | Block 21, offshore Angola | CIE Angola Block 21 Ltd
Angola Transaction
Percentage of working interest acquired	60.00%

Seismic and Exploration Expen44

Seismic and Exploration Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Seismic and Exploration Expenses
Seismic costs	$ 8,771	$ 8,173	$ 28,572	$ 10,478
Leasehold delay rentals	872	1,125	5,198	5,547
Other exploration expense	749	572	1,956	2,155
Total seismic and exploration expenses	$ 10,392	$ 9,870	$ 35,726	$ 18,180

Equity Based Compensation (Deta

Equity Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 20, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Apr. 30, 2015
Number of Stock Options
Equity based compensation expense, net of forfeitures recognized		$ 6,500	$ 7,800	$ 19,695	$ 23,102
2015 Long Term Incentive Plan (the "2015 Plan")
Restricted Shares
Awards granted (in shares)				150,000
Common Stock | 2015 Long Term Incentive Plan (the "2015 Plan")
Number of Stock Options
Shares available for grant under the plan						12,000,000
Restricted Stock
Restricted Shares
Granted (in shares)				3,503,948
Restricted Stock | Three senior officers
Restricted Shares
Granted (in shares)				379,746
Retainer awards | Non-employee directors | Common Stock
Restricted Shares
Awards granted (in shares)				35,814
Non-Qualified Stock Options
Number of Stock Options
Granted (in shares)				746,268
Non-Qualified Stock Options | Three senior officers
Number of Stock Options
Granted (in shares)				746,268
Stock appreciation rights ("SARs") | Long Term Incentive Plan (the ?Plan?)
Number of Stock Options
Total shares issues	1,526,835
Market price at the time of issuance	$ 8.87
vesting percentage	33.00%
Vesting period	3 years
Fair value of share ( in dollars per share)	$ 4.53			$ 3.52
Reduction in aggregate fair value				$ 800
Stock compensation expense		$ 200		$ 1,000
Restricted stock units awards | Non-employee directors
Restricted Shares
Awards granted (in shares)				105,846