Gran Tierra Energy (GTE) 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	GRAN TIERRA ENERGY INC.
Entity Central Index Key	1,273,441
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		388,415,513
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
OIL AND NATURAL GAS SALES (NOTE 3)	$ 103,768	$ 68,539	$ 294,555	$ 197,655
EXPENSES
Operating	27,321	25,638	78,466	62,453
Transportation	6,038	5,773	19,472	24,318
Depletion, depreciation and accretion (Note 3)	34,492	35,729	92,729	104,525
Asset impairment (Notes 3 and 4)	787	319,974	1,239	469,715
General and administrative (Note 3)	8,651	5,592	26,876	20,614
Severance	1,164	0	1,164	1,299
Transaction	0	6,088	0	7,325
Equity tax	0	0	1,224	3,053
Foreign exchange (gain) loss	(1,271)	(507)	779	1,059
Financial instruments loss (gain) (Note 10)	1,675	2,051	(5,211)	1,824
Interest expense (Note 5)	3,989	5,122	10,415	7,842
EXPENSES	82,846	405,460	227,153	704,027
LOSS ON SALE OF BRAZIL BUSINESS UNIT (NOTE 4)	0	0	(9,076)	0
GAIN ON ACQUISITION	0	0	0	11,712
INTEREST INCOME	301	730	954	1,928
INCOME (LOSS) BEFORE INCOME TAXES (NOTE 3)	21,223	(336,191)	59,280	(492,732)
INCOME TAX EXPENSE (RECOVERY)
Current	4,333	3,879	13,522	11,680
Deferred	13,760	(110,451)	36,664	(166,202)
INCOME TAX EXPENSE (RECOVERY)	18,093	(106,572)	50,186	(154,522)
NET INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS)	$ 3,130	$ (229,619)	$ 9,094	$ (338,210)
NET INCOME (LOSS) PER SHARE - BASIC AND DILUTED (in dollars per share)	$ 0.01	$ (0.71)	$ 0.02	$ (1.11)
WEIGHTED AVERAGE SHARES OUTSTANDING - BASIC (in shares)	394,771,194	321,725,379	397,439,007	304,098,944
WEIGHTED AVERAGE SHARES OUTSTANDING - DILUTED (in shares)	394,774,953	321,725,379	397,450,637	304,098,944

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents (Note 11)	$ 15,125	$ 25,175
Restricted cash and cash equivalents (Notes 7 and 11)	3,920	8,322
Accounts receivable	38,279	45,698
Derivatives (Note 10)	512	578
Inventory (Note 4)	6,978	7,766
Taxes receivable	34,879	26,393
Prepaid taxes (Note 2)	0	12,271
Other prepaids	2,194	5,482
Total Current Assets	101,887	131,685
Oil and Gas Properties (using the full cost method of accounting)
Proved	508,981	412,319
Unproved	613,419	647,774
Total Oil and Gas Properties	1,122,400	1,060,093
Other capital assets	5,224	6,516
Total Property, Plant and Equipment (Notes 3 and 4)	1,127,624	1,066,609
Other Long-Term Assets
Deferred tax assets (Note 2)	66,963	1,611
Prepaid taxes (Note 2)	0	41,784
Restricted cash and cash equivalents (Notes 7 and 11)	10,332	9,770
Other long-term assets	13,789	13,856
Goodwill (Note 3)	102,581	102,581
Total Other Long-Term Assets	193,665	169,602
Total Assets	1,423,176	1,367,896
Current Liabilities
Accounts payable and accrued liabilities	119,829	107,051
Derivatives (Note 10)	65	3,824
Taxes payable (Note 2)	2,419	38,939
Asset retirement obligation (Note 7)	355	5,215
Total Current Liabilities	122,668	155,029
Long-Term Liabilities
Long-term debt (Notes 5 and 10)	229,215	197,083
Deferred tax liabilities (Note 2)	29,368	107,230
Asset retirement obligation (Note 7)	43,649	38,142
Other long-term liabilities	13,816	11,425
Total Long-Term Liabilities	316,048	353,880
Contingencies (Note 9)
Shareholders’ Equity
Common Stock (Note 6) (386,872,530 and 390,807,194 shares of Common Stock and 7,898,664 and 8,199,894 exchangeable shares, par value $0.001 per share, issued and outstanding as at September 30, 2017, and December 31, 2016, respectively)	10,299	10,303
Additional paid in capital	1,334,563	1,342,656
Deficit	(360,402)	(493,972)
Total Shareholders’ Equity	984,460	858,987
Total Liabilities and Shareholders’ Equity	$ 1,423,176	$ 1,367,896

Condensed Consolidated Balance4

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common Stock, shares issued	386,872,530	390,807,194
Common Stock, shares outstanding	386,872,530	390,807,194
Exchangeable shares, shares issued	7,898,664	8,199,894
Exchangeable shares, shares outstanding	7,898,664	8,199,894
Common Stock and exchangeable shares, par value (in dollars per share)	$ 0.001	$ 0.001

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating Activities
Net income (loss)	$ 9,094	$ (338,210)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depletion, depreciation and accretion (Note 3)	92,729	104,525
Asset impairment (Notes 3 and 4)	1,239	469,715
Deferred tax expense (recovery)	36,664	(166,202)
Stock-based compensation (Note 6)	4,935	4,380
Amortization of debt issuance costs (Note 5)	1,868	2,813
Cash settlement of restricted share units	(534)	(1,210)
Unrealized foreign exchange (gain) loss	(304)	2,437
Financial instruments (gain) loss (Note 10)	(5,211)	1,824
Cash settlement of financial instruments (Note 10)	1,518	438
Cash settlement of asset retirement obligation (Note 7)	(462)	(496)
Loss on sale of Brazil business unit (Note 4)	9,076	0
Gain on acquisition	0	(11,712)
Net change in assets and liabilities from operating activities (Note 11)	(28,105)	18,097
Net cash provided by operating activities	122,507	86,399
Investing Activities
Additions to property, plant and equipment (Note 3)	(175,719)	(69,667)
Additions to property, plant and equipment - property acquisitions (Note 4)	(30,410)	(19,388)
Net proceeds from sale of Brazil business unit (Note 4)	34,481	0
Cash deposit received for letter of credit arrangements upon sale of Brazil business unit (Note 4)	4,700	0
Cash paid for business combinations, net of cash acquired	0	(457,183)
Proceeds from sale of marketable securities	0	788
Changes in non-cash investing working capital	11,347	(8,036)
Net cash used in investing activities	(155,601)	(553,486)
Financing Activities
Proceeds from bank debt, net of issuance costs (Note 5)	115,264	220,169
Repayment of bank debt (Note 5)	(85,000)	(110,181)
Proceeds from issuance of shares of Common Stock, net of issuance costs	0	5,169
Repurchase of shares of Common Stock (Note 6)	(10,000)	0
Proceeds from issuance of subscription receipts, net of issuance costs	0	165,805
Proceeds from issuance of Convertible Senior Notes, net of issuance costs (Note 5)	0	109,090
Net cash provided by financing activities	20,264	390,052
Foreign exchange loss on cash, cash equivalents and restricted cash and cash equivalents	(1,060)	(452)
Net decrease in cash, cash equivalents and restricted cash and cash equivalents	(13,890)	(77,487)
Cash, cash equivalents and restricted cash and cash equivalents, beginning of period (Note 11)	43,267	148,751
Cash, cash equivalents and restricted cash and cash equivalents, end of period (Note 11)	$ 29,377	$ 71,264

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Share Capital	Additional Paid in Capital	Deficit
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment for accounting change related to tax reorganizations (Note 2)				$ 0
Balance, beginning of period at Dec. 31, 2015		$ 10,186	$ 1,019,863	(28,407)
Increase (Decrease) in Stockholders' Equity
Issuance of Common Stock		117	314,425
Exercise of stock options			5,347
Stock-based compensation (Note 6)			3,021
Repurchase of Common Stock (Note 6)		0	0
Net income (loss)				(465,565)
Balance, end of period at Dec. 31, 2016	$ 858,987	10,303	1,342,656	(493,972)
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment for accounting change related to tax reorganizations (Note 2)				124,476
Issuance of Common Stock		0	0
Exercise of stock options			0
Stock-based compensation (Note 6)			1,903
Repurchase of Common Stock (Note 6)		(4)	(9,996)
Net income (loss)	9,094			9,094
Balance, end of period at Sep. 30, 2017	$ 984,460	$ 10,299	$ 1,334,563	$ (360,402)

Description of Business

Description of Business	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Gran Tierra Energy Inc., a Delaware corporation (the “Company” or “Gran Tierra”), is a publicly traded company focused on oil and natural gas exploration and production in Colombia. The Company also has business activities in Peru and, until June 30, 2017, had business activities in Brazil.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies These interim unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”). The information furnished herein reflects all normal recurring adjustments that are, in the opinion of management, necessary for the fair presentation of results for the interim periods. The note disclosure requirements of annual consolidated financial statements provide additional disclosures to that required for interim unaudited condensed consolidated financial statements. Accordingly, these interim unaudited condensed consolidated financial statements should be read in conjunction with the Company’s consolidated financial statements as at and for the year ended December 31, 2016 , included in the Company’s 2016 Annual Report on Form 10-K, filed with the SEC on March 1, 2017 . The Company’s significant accounting policies are described in Note 2 of the consolidated financial statements which are included in the Company’s 2016 Annual Report on Form 10-K and are the same policies followed in these interim unaudited condensed consolidated financial statements, except as noted below. The Company has evaluated all subsequent events through to the date these interim unaudited condensed consolidated financial statements were issued. Recently Adopted Accounting Pronouncements Simplifying the Measurement of Inventory In July 2015, the Financial Accounting Standards Board (“FASB”) issued ASU 2015-11, “Simplifying the Measurement of Inventory". The ASU provides guidance for the subsequent measurement of inventory and requires that inventory that is measured using average cost be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The ASU was effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The implementation of this update did not materially impact the Company’s consolidated financial position, results of operations or cash flows or disclosure. Employee Share-Based Payment Accounting In March 2016, the FASB issued ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting ". This ASU simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for forfeitures, income taxes, and statutory tax withholding requirements. The ASU was effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The Company elected to continue to estimate the total number of awards for which the requisite service period will not be rendered. The implementation of this update did not impact the Company’s consolidated financial position, results of operations or cash flows or disclosure. Income Taxes - Intra-Entity Transfers of Assets Other than Inventory At December 31, 2016, GAAP prohibited the recognition of current and deferred income taxes for intra-entity transfers until an asset leaves the consolidated group, therefore, the current income tax effect of tax reorganizations completed in 2016 was deferred and recognized as prepaid income taxes. At December 31, 2016, the Company's balance sheet included $54.1 million of prepaid income taxes, $12.3 million in current prepaid taxes and $41.8 million in long-term prepaid taxes, and $37.5 million of current income taxes payable relating to tax reorganizations completed in 2016. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other than Inventory." This ASU requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense or benefit in the period the sale or transfer occurs. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those years. Early adoption was permitted as of the beginning of an annual reporting period. The ASU is required to be applied on a modified retrospective basis with a cumulative-effect adjustment directly to retained earnings in the period of adoption. The Company early adopted this ASU on January 1, 2017, and in the three months ending March 31, 2017, wrote off the income tax effects that had been deferred from past intercompany transactions to opening deficit. Prepaid tax of $54.1 million and deferred tax assets of $178.6 million were recorded directly to opening deficit at January 1, 2017. Deferred tax assets recorded upon adoption were assessed for realizability under Accounting Standards Codification ("ASC") 740 "Income Taxes", and, valuation allowances were recognized on those deferred tax assets as necessary on the date of adoption. The adoption of ASU 2016-16 did not have any effect on the Company’s cash flows. Restricted Cash and Cash Equivalents In November 2016, the FASB issued ASU 2016-18, "Restricted Cash". ASU 2016-18 requires that a statement of cash flows explain the change during the period in the total cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. ASU 2016-18 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2017. Early adoption was permitted. The Company early adopted this ASU on January 1, 2017, on a retrospective basis to each period presented. The implementation of this ASU did not impact the Company's consolidated financial position or results of operations. For the nine months ended September 30, 2016 , the net decrease in cash, cash equivalents and restricted cash and cash equivalents currently disclosed was $77.5 million , compared with the net decrease in cash and cash equivalents of $97.3 million as previously disclosed in the consolidated statement of cash flows prior to the adoption of ASU 2016-18. Clarifying the Definition of a Business In January 2017, the FASB issued ASU 2017-01, "Clarifying the Definition of a Business". ASU 2017-01 narrows the definition of a business and provides a framework that gives entities a basis for making reasonable judgments about whether a transaction involves an asset or a business. ASU 2017-01 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2017. Early adoption was permitted and the Company adopted this ASU on January 1, 2017. The Company now applies an initial screen for determining whether a transaction involves an asset or a business. When substantially all of the fair value of the gross assets acquired is concentrated in a single identified asset, or group of similar identifiable assets, the set will not be a business and no goodwill or gain on acquisition will be recognized. If the screen is not met, a set cannot be considered a business unless it includes an input and a substantive process that together significantly contribute to the ability to create an output. The Company’s acquisition of the Santana and Nancy Burdine-Maxine oil and gas properties in the nine months ended September 30, 2017 was not considered a business under this ASU and therefore not allocated goodwill or gain on acquisition (Note 4). Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU 2017-04, "Simplifying the Test for Goodwill Impairment". ASU 2017-04 eliminates step 2 of the goodwill impairment test. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. ASU 2017-04 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2019. Early adoption is permitted. At September 30, 2017 , the Company performed a qualitative assessment of goodwill and, based on this assessment, no impairment of goodwill was identified. The Company did not have to perform step 2 of the goodwill impairment test. Recently Issued Accounting Pronouncements Revenue from Contracts with Customers In May 2014, the FASB issued guidance regarding the accounting for revenue from contracts with customers. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers - Deferral of the Effective Date". The ASU deferred the effective date of the new revenue recognition model by one year. As a result, the guidance will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. In March 2016, the FASB issued ASU 2016-08, “Principal versus Agent Considerations (Reporting Revenue Gross versus Net)" which clarifies implementation guidance on principal versus agent considerations. In April, May and December 2016, the FASB issued ASU 2016-10, “Identifying Performance Obligations and Licensing", ASU 2016-12, “Narrow-Scope Improvements and Practical Expedients" and ASU 2016-20 "Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers", respectively, which addressed implementation issues and provided technical corrections. The guidance may be applied retrospectively or using a modified retrospective approach to adjust retained earnings. The Company is continuing to evaluate the impact of the ASU and currently expects that the standard will not have a material impact on the Company’s consolidated financial statements other than enhanced disclosures related to revenues from contracts with customers. The Company intends to adopt the new standard using the modified retrospective method at the date of adoption, which is expected to be January 1, 2018.

Segment and Geographic Reportin

Segment and Geographic Reporting	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment and Geographic Reporting	Segment and Geographic Reporting The Company is primarily engaged in the exploration and production of oil and natural gas. The Company’s reportable segments are Colombia and Peru, based on geographic organization. Prior to the sale of the Company’s Brazil business unit effective June 30, 2017, (Note 4), Brazil was a reportable segment. The All Other category represents the Company’s corporate and Mexico activities. The Company evaluates reportable segment performance based on income or loss before income taxes. The following tables present information on the Company’s reportable segments and other activities: Three Months Ended September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 103,768 $ — $ — $ — $ 103,768 Depletion, depreciation and accretion 33,388 881 — 223 34,492 Asset impairment — 176 — 611 787 General and administrative expenses 5,500 301 — 2,850 8,651 Income (loss) before income taxes 31,276 (1,405 ) — (8,648 ) 21,223 Segment capital expenditures 70,606 998 — 90 71,694 Three Months Ended September 30, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 65,944 $ — $ 2,595 $ — $ 68,539 Depletion, depreciation and accretion 34,156 206 1,022 345 35,729 Asset impairment 298,370 — 21,604 — 319,974 General and administrative expenses 1,921 218 218 3,235 5,592 Loss before income taxes (299,306 ) (768 ) (20,977 ) (15,140 ) (336,191 ) Segment capital expenditures 20,476 1,360 3,102 142 25,080 Nine Months Ended September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 286,137 $ — $ 8,418 $ — $ 294,555 Depletion, depreciation and accretion 88,453 1,350 2,263 663 92,729 Asset impairment — 628 — 611 1,239 General and administrative expenses 15,561 974 743 9,598 26,876 Income (loss) before income taxes 90,018 (2,685 ) 3,369 (31,422 ) 59,280 Segment capital expenditures 168,881 3,207 2,811 820 175,719 Nine Months Ended September 30, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 191,515 $ — $ 6,140 $ — $ 197,655 Depletion, depreciation and accretion 100,350 418 2,764 993 104,525 Asset impairment 431,810 899 37,006 — 469,715 General and administrative expenses 9,614 1,014 751 9,235 20,614 Loss before income taxes (436,863 ) (2,224 ) (36,523 ) (17,122 ) (492,732 ) Segment capital expenditures 56,997 3,730 7,982 958 69,667 As at September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Property, plant and equipment $ 1,054,136 $ 70,903 $ — $ 2,585 $ 1,127,624 Goodwill 102,581 — — — 102,581 All other assets 176,672 11,103 — 5,196 192,971 Total Assets $ 1,333,389 $ 82,006 $ — $ 7,781 $ 1,423,176 As at December 31, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Property, plant and equipment $ 939,947 $ 68,428 $ 55,196 $ 3,038 $ 1,066,609 Goodwill 102,581 — — — 102,581 All other assets 177,393 10,848 1,619 8,846 198,706 Total Assets $ 1,219,921 $ 79,276 $ 56,815 $ 11,884 $ 1,367,896

Property, Plant and Equipment a

Property, Plant and Equipment and Inventory	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment and Inventory	Property, Plant and Equipment and Inventory Property, Plant and Equipment (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Oil and natural gas properties Proved $ 2,836,263 $ 2,652,171 Unproved 613,419 647,774 3,449,682 3,299,945 Other 27,236 29,445 3,476,918 3,329,390 Accumulated depletion, depreciation and impairment (2,349,294 ) (2,262,781 ) $ 1,127,624 $ 1,066,609 Asset impairment for the three and nine months ended September 30, 2017 , and 2016 was as follows: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Impairment of oil and gas properties $ 787 $ 319,974 $ 1,239 $ 469,051 Impairment of inventory — — — 664 $ 787 $ 319,974 $ 1,239 $ 469,715 The Company follows the full cost method of accounting for its oil and gas properties. Under this method, the net book value of properties on a country-by-country basis, adjusted for related deferred income taxes, may not exceed a calculated “ceiling”. The ceiling is the estimated after tax future net revenues from proved oil and gas properties, discounted at 10% per year. In calculating discounted future net revenues, oil and natural gas prices are determined using the average price during the 12 months period prior to the ending date of the period covered by the balance sheet, calculated as an unweighted arithmetic average of the first-day-of-the month price for each month within such period for that oil and natural gas. That average price is then held constant, except for changes which are fixed and determinable by existing contracts. Therefore, ceiling test estimates are based on historical prices discounted at 10% per year and it should not be assumed that this estimate of future net revenues represent the fair market value of the Company's reserves. In accordance with GAAP, Gran Tierra used an average Brent price of $52.70 per bbl for the purposes of the September 30, 2017 ceiling test calculations ( June 30, 2017 - $51.35 ; March 31, 2017 - $49.33 ; December 31, 2016 - $42.92 ; September 30, 2016 - $42.23 ; June 30, 2016 - $44.48 ; March 31, 2016 - $48.79 ; December 31, 2015 - $54.08 ). Acquisition of Santana and Nancy Burdine-Maxine Blocks On April 27, 2017 , the Company acquired the Santana and Nancy-Burdine-Maxine Blocks in the Putumayo Basin for cash consideration of $30.4 million . The acquisition was accounted for as an asset acquisition with the consideration paid allocated on a relative fair value basis to the net assets acquired. The following table shows the allocation of the cost of the acquisition based on the relative fair values of the assets and liabilities acquired: (Thousands of U.S. Dollars) Cost of asset acquisition: Cash $ 30,410 Allocation of Consideration Paid: Oil and gas properties Proved $ 24,405 Unproved 8,649 33,054 Inventory 869 Asset retirement obligation - long-term (3,513 ) $ 30,410 Disposition of Brazil Business Unit On June 30, 2017, the Company, through two of its indirect subsidiaries (the “Selling Subsidiaries”), completed the previously announced disposition of its assets in Brazil. Gran Tierra completed the disposition of its Brazil business unit for a purchase price of $35.0 million which, after certain interim closing adjustments, resulted in cash consideration paid to the Selling Subsidiaries of approximately $38.0 million . At December 31, 2016, assets and liabilities of the Brazil business unit were as follows: (Thousands of U.S. Dollars) As at December 31, 2016 Current assets $ 1,634 Property, plant and equipment 55,376 $ 57,010 Current liabilities $ (11,590 ) Long-term liabilities (2,297 ) $ (13,887 ) At June 30, 2017, the net book value of the Brazil business unit was greater than the proceeds received resulting in a $9.1 million loss on sale. Gran Tierra also received a $4.7 million cash payment from the purchaser reflecting the covenant by the purchaser to finalize the documentation and other arrangements to assume liabilities associated with letter of credit arrangements and the release of Gran Tierra from any liabilities in connection with the same, which payment will be reimbursable to the purchaser once such covenant is discharged. Inventory At September 30, 2017 , oil and supplies inventories were $4.5 million and $2.5 million , respectively ( December 31, 2016 - $6.0 million and $1.8 million , respectively). At September 30, 2017 , the Company had 168 Mbbl of oil inventory ( December 31, 2016 - 208 Mbbl). In each of the three and nine months ended September 30, 2017 , the Company recorded oil inventory impairment of $ nil (three and nine months ended September 30, 2016 - $ nil and $ 0.7 million , respectively) related to lower oil prices.

Debt and Interest Expense

Debt and Interest Expense	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Debt and Interest Expense	Debt and Interest Expense At September 30, 2017 , the Company had a revolving credit facility with a syndicate of lenders with a borrowing base of $300 million . Availability under the revolving credit facility is determined by the reserves-based borrowing base determined by the lenders. As a result of the semi-annual redetermination, the committed borrowing base was increased from $250 million to $300 million effective June 1, 2017. The next re-determination of the borrowing base is due to occur no later than November 2017. On September 18, 2017, the Company entered into the Eighth Amendment to the credit agreement with the other parties thereto, which, among other things, extended the maturity date of the borrowings under the revolving credit facility from September 18, 2018, to October 1, 2018. The Company's debt at September 30, 2017 , and December 31, 2016 , was as follows: (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Convertible senior notes $ 115,000 $ 115,000 Revolving credit facility 120,000 90,000 Unamortized debt issuance costs (5,785 ) (7,917 ) Long-term debt $ 229,215 $ 197,083 The following table presents total interest expense recognized in the accompanying interim unaudited condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Contractual interest and other financing expenses $ 3,346 $ 2,938 $ 8,547 $ 5,029 Amortization of debt issuance costs 643 2,184 1,868 2,813 $ 3,989 $ 5,122 $ 10,415 $ 7,842

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share Capital	Share Capital The Company’s authorized share capital consists of 595,000,002 shares of capital stock, of which 570 million are designated as Common Stock, par value $0.001 per share, 25 million are designated as Preferred Stock, par value $0.001 per share, one share is designated as Special A Voting Stock, par value $0.001 per share, and one share is designated as Special B Voting Stock, par value $0.001 per share. Shares of Common Stock Exchangeable Shares of Gran Tierra Exchangeco Inc. Exchangeable Shares of Gran Tierra Goldstrike Inc. Balance, December 31, 2016 390,807,194 4,812,592 3,387,302 Shares repurchased and canceled (4,235,890 ) — — Exchange of exchangeable shares 301,230 (142,500 ) (158,730 ) Shares canceled (4 ) — — Balance, September 30, 2017 386,872,530 4,670,092 3,228,572 On February 6, 2017, the Company announced that it had implemented a new share repurchase program (the “2017 Program”) through the facilities of the Toronto Stock Exchange ("TSX"), the NYSE American and eligible alternative trading platforms in Canada and the United States. Under the 2017 Program, the Company is able to purchase at prevailing market prices up to 19,540,359 shares of Common Stock, representing 5.0% of the issued and outstanding shares of Common Stock as of January 27, 2017. Shares purchased pursuant to the 2017 Program will be canceled. The 2017 Program will expire on February 7, 2018, or earlier if the 5.0% share maximum is reached. Equity Compensation Awards The following table provides information about p erformance stock units (“PSUs”), deferred share units (“DSUs”), restricted stock units (“RSUs”) and stock option activity for the nine months ended September 30, 2017 : PSUs DSUs RSUs Stock Options Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Stock Options Weighted Average Exercise Price/Stock Option ($) Balance, December 31, 2016 3,362,717 208,698 359,145 9,239,478 4.16 Granted 3,229,620 171,388 — 1,964,156 2.54 Exercised — — (211,022 ) — — Forfeited (641,159 ) — (9,402 ) (903,910 ) (4.81 ) Expired — — — (1,396,667 ) (4.65 ) Balance, September 30, 2017 5,951,178 380,086 138,721 8,903,057 3.66 Stock-based compensation expense for the three and nine months ended September 30, 2017 , was $1.8 million and $4.9 million , respectively, and was primarily recorded in general and administrative ("G&A") expenses (three and nine months ended September 30, 2016 - $0.9 million and $4.4 million , respectively). At September 30, 2017 , there was $11.5 million ( December 31, 2016 - $10.0 million ) of unrecognized compensation cost related to unvested PSUs, RSUs and stock options which is expected to be recognized over a weighted average period of 1.7 years. Net Income (Loss) per Share Basic net income (loss) per share is calculated by dividing net income (loss) attributable to common shareholders by the weighted average number of shares of Common Stock and exchangeable shares issued and outstanding during each period. Diluted net income (loss) per share is calculated by adjusting the weighted average number of shares of Common Stock and exchangeable shares outstanding for the dilutive effect, if any, of share equivalents. The Company uses the treasury stock method to determine the dilutive effect. This method assumes that all Common Stock equivalents have been exercised at the beginning of the period (or at the time of issuance, if later), and that the funds obtained thereby were used to purchase shares of Common Stock of the Company at the volume weighted average trading price of shares of Common Stock during the period. Weighted Average Shares Outstanding Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Weighted average number of common and exchangeable shares outstanding 394,771,194 321,725,379 397,439,007 304,098,944 Shares issuable pursuant to stock options 61,325 — 187,150 — Shares assumed to be purchased from proceeds of stock options (57,566 ) — (175,520 ) — Weighted average number of diluted common and exchangeable shares outstanding 394,774,953 321,725,379 397,450,637 304,098,944 For the three months ended September 30, 2017 , 9,259,811 options, on a weighted average basis, ( three months ended September 30, 2016 - 9,084,162 options) were excluded from the diluted income (loss) per share calculation as the options were anti-dilutive. For the nine months ended September 30, 2017 , 9,744,747 options, on a weighted average basis, ( nine months ended September 30, 2016 - 11,155,962 options) were excluded from the diluted income (loss) per share calculation as the options were anti-dilutive. Shares issuable upon conversion of the 5.00% Convertible Senior Notes due 2021 ("Notes") were anti-dilutive and excluded from the diluted income (loss) per share calculation.

Asset Retirement Obligation

Asset Retirement Obligation	9 Months Ended
	Sep. 30, 2017
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	Asset Retirement Obligation Changes in the carrying amounts of the asset retirement obligation associated with the Company’s oil and natural gas properties were as follows: Nine Months Ended Year Ended (Thousands of U.S. Dollars) September 30, 2017 December 31, 2016 Balance, beginning of period $ 43,357 $ 33,224 Liability incurred 2,942 2,606 Liabilities assumed in acquisition 3,513 15,723 Accretion 3,101 2,789 Settlements (1,039 ) (872 ) Liabilities associated with assets sold (2,200 ) (3,257 ) Revisions in estimated liability (5,670 ) (6,856 ) Balance, end of period $ 44,004 $ 43,357 Asset retirement obligation - current $ 355 $ 5,215 Asset retirement obligation - long-term 43,649 38,142 $ 44,004 $ 43,357 For the nine months ended September 30, 2017 , settlements included $0.5 million cash payments with the balance in accounts payable and accrued liabilities at September 30, 2017 . Revisions in estimated liabilities relate primarily to changes in estimates of asset retirement costs and include, but are not limited to, revisions of estimated inflation rates, changes in property lives and the expected timing of settling asset retirement obligations. At September 30, 2017 , the fair value of assets that are legally restricted for purposes of settling the asset retirement obligation was $12.6 million ( December 31, 2016 - $12.0 million ). These assets are accounted for as restricted cash and cash equivalents on the Company's interim unaudited condensed consolidated balance sheets.

Taxes

Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Taxes	Taxes The Company's effective tax rate was 85% in the nine months ended September 30, 2017 , compared with 31% in the corresponding period in 2016 . The Company's effective tax rate differed from the U.S. statutory rate of 35% primarily due to impact of foreign taxes, valuation allowance, non-deductible third-party royalty in Colombia, stock-based compensation and other local taxes. These items were partially offset by foreign currency translation adjustments.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Agencia Nacional de Hidrocarburos (National Hydrocarbons Agency) (“ANH") and Gran Tierra are engaged in ongoing discussions regarding the interpretation of whether certain transportation and related costs are eligible to be deducted in the calculation of an additional royalty (the "HPR royalty"). Based on the Company's understanding of the ANH's position, the estimated compensation which would be payable if the ANH’s interpretation is correct could be up to $49.8 million as at September 30, 2017 . At this time no amount has been accrued in the interim unaudited condensed consolidated financial statements as Gran Tierra does not consider it probable that a loss will be incurred. In addition to the above, the Company has a number of other lawsuits and claims pending. Although the outcome of these other lawsuits and disputes cannot be predicted with certainty, the Company believes the resolution of these matters would not have a material adverse effect on the Company’s consolidated financial position, results of operations or cash flows. Gran Tierra records costs associated with these lawsuits and claims as they are incurred or become probable and determinable. Letters of credit and other credit support At September 30, 2017 , the Company had provided letters of credit and other credit support totaling $74.5 million ( December 31, 2016 - $96.8 million ) as security relating to work commitment guarantees contained in exploration contracts and other capital or operating requirements.

Financial Instruments and Fair

Financial Instruments and Fair Value Measurement	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value Measurement	Financial Instruments and Fair Value Measurement Financial Instruments At September 30, 2017 , the Company’s financial instruments recognized in the balance sheet consist of: cash and cash equivalents; restricted cash and cash equivalents; accounts receivable; derivatives, accounts payable and accrued liabilities, long-term debt, PSU liability included in other long-term liabilities, and RSU liability included in accounts payable and accrued liabilities and other long-term liabilities. Fair Value Measurement The fair value of derivatives and RSU and PSU liabilities are being remeasured at the estimated fair value at the end of each reporting period. The fair value of commodity price and foreign currency derivatives is estimated based on various factors, including quoted market prices in active markets and quotes from third parties. The Company also performs an internal valuation to ensure the reasonableness of third party quotes. In consideration of counterparty credit risk, the Company assessed the possibility of whether the counterparty to the derivative would default by failing to make any contractually required payments. Additionally, the Company considers that it is of substantial credit quality and has the financial resources and willingness to meet its potential repayment obligations associated with the derivative transactions. The fair value of the RSU liability was estimated based on quoted market prices in an active market. The fair value of the PSU liability was estimated based on quoted market prices in an active market and an option pricing model such as the Monte Carlo simulation option-pricing models. The fair value of derivatives and RSU, PSU and DSU liabilities at September 30, 2017 , and December 31, 2016 , were as follows: (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Foreign currency derivative asset $ 512 $ 578 Commodity price derivative liability $ 65 $ 3,824 RSU, PSU and DSU liability 6,851 3,907 $ 6,916 $ 7,731 The following table presents gains or losses on financial instruments recognized in the accompanying interim unaudited condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Commodity price derivative loss (gain) $ 2,489 $ 2,190 $ (3,759 ) $ 856 Foreign currency derivatives gain (814 ) (840 ) (1,452 ) (1,958 ) Trading securities loss — 701 — 2,926 Financial instruments loss (gain) $ 1,675 $ 2,051 $ (5,211 ) $ 1,824 These gains and losses are presented as financial instrument gains and losses in the interim unaudited condensed consolidated statements of operations and cash flows. Financial instruments not recorded at fair value include the Notes. At September 30, 2017 , the carrying amount of the Notes was $110.7 million , which represents the aggregate principal amount less unamortized debt issuance costs, and the fair value was $121.9 million . The fair value of long-term restricted cash and cash equivalents and the revolving credit facility approximated their carrying value because interest rates are variable and reflective of market rates. The fair values of other financial instruments approximate their carrying amounts due to the short-term maturity of these instruments. GAAP establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. This hierarchy consists of three broad levels. Level 1 inputs consist of quoted prices (unadjusted) in active markets for identical assets and liabilities and have the highest priority. Level 2 and 3 inputs are based on significant other observable inputs and significant unobservable inputs, respectively, and have lower priorities. The Company uses appropriate valuation techniques based on the available inputs to measure the fair values of assets and liabilities. At September 30, 2017 , the fair value of the derivatives was determined using Level 2 inputs and the fair value of the PSU liability was determined using Level 3 inputs. The Company uses available market data and valuation methodologies to estimate the fair value of debt. The fair value of debt is the estimated amount the Company would have to pay a third party to assume the debt, including a credit spread for the difference between the issue rate and the period end market rate. The credit spread is the Company’s default or repayment risk. The credit spread (premium or discount) is determined by comparing the Company’s Notes and revolving credit facility to new issuances (secured and unsecured) and secondary trades of similar size and credit statistics for both public and private debt. The disclosure above regarding the fair value of the Company’s revolving credit facility was determined using an income approach using Level 3 inputs. The disclosure above regarding the fair value of the Notes was determined using Level 2 inputs based on the indicative pricing published by certain investment banks or trading levels of the Notes, which are not listed on any securities exchange or quoted on an inter-dealer automated quotation system. The disclosure in the paragraph above regarding the fair value of cash and cash equivalents and restricted cash and cash equivalents was based on Level 1 inputs. The Company’s non-recurring fair value measurements include asset retirement obligations. The fair value of an asset retirement obligation is 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. The significant level 3 inputs used to calculate such liabilities include estimates of costs to be incurred, the Company’s credit-adjusted risk-free interest rate, inflation rates and estimated dates of abandonment. Accretion expense is recognized over time as the discounted liabilities are accreted to their expected settlement value, while the asset retirement cost is amortized over the estimated productive life of the related assets. Commodity Price Derivatives The Company utilizes commodity price derivatives to manage the variability in cash flows associated with the forecasted sale of its oil production, reduce commodity price risk and provide a base level of cash flow in order to assure it can execute at least a portion of its capital spending. At September 30, 2017 , the Company had outstanding commodity price derivative positions as follows: Period and type of instrument Volume, Reference Sold Put ($/bbl) Purchased Put Sold Call ($/bbl) Collar: October 1, 2016 to December 31, 2017 5,000 ICE Brent $ 35 $ 45 $ 65 Collar: June 1, 2017 to December 31, 2017 10,000 ICE Brent $ 35 $ 45 $ 65 Subsequent to September 30, 2017, the Company entered into the following commodity price contracts: Period and type of instrument Volume, Reference Purchased Swap Purchased Call ($/bbl) Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 55.75 Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 56.05 Participating Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 50.00 $ 54.10 Foreign Currency Derivatives The Company utilizes foreign currency derivatives to manage the variability in cash flows associated with the Company's forecasted Colombian peso ("COP") denominated expenses. At September 30, 2017 , the Company had outstanding foreign currency derivative positions as follows: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (1) (Thousands of U.S. Dollars) Reference Purchased Call Sold Put Collar: October 1, 2017 to October 31, 2017 23,000 7,832 COP 3,000 3,117 Collar: November 1, 2017 to November 30, 2017 25,000 8,513 COP 3,000 3,139 Collar: December 1, 2017 to December 28, 2017 25,000 8,513 COP 3,000 3,142 73,000 24,858 (1) At September 30, 2017 foreign exchange rate. Subsequent to September 30, 2017, the Company entered into the following foreign currency contracts: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (1) (Thousands of U.S. Dollars) Reference Purchased Call Sold Put Collar: January 1, 2018 to December 31, 2018 132,000 44,949 COP 3,000 3,112 (1) At September 30, 2017 foreign exchange rate.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table provides a reconciliation of cash, cash equivalents and restricted cash and cash equivalents with the Company's interim unaudited condensed consolidated balance sheet that sum to the total of the same such amounts shown in the interim unaudited condensed consolidated statements of cash flows: (Thousands of U.S. Dollars) As at September 30, As at December 31, 2017 2016 2016 2015 Cash and cash equivalents $ 15,125 $ 48,073 $ 25,175 $ 145,342 Restricted cash and cash equivalents - current 3,920 13,198 8,322 92 Restricted cash and cash equivalents - long-term 10,332 9,993 9,770 3,317 $ 29,377 $ 71,264 $ 43,267 $ 148,751 Net changes in assets and liabilities from operating activities were as follows: Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 Accounts receivable and other long-term assets $ 8,356 $ 15,233 Derivatives — (4,563 ) Inventory (28 ) 3,630 Prepaids 3,080 1,864 Accounts payable and accrued and other long-term liabilities 5,951 (11,297 ) Taxes receivable and payable (45,464 ) 13,230 Net changes in assets and liabilities from operating activities $ (28,105 ) $ 18,097 The following table provides additional supplemental cash flow disclosures: Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 Non-cash investing activities: Net liabilities related to property, plant and equipment, end of period $ 68,018 $ 27,520

Significant Accounting Polici18

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements Simplifying the Measurement of Inventory In July 2015, the Financial Accounting Standards Board (“FASB”) issued ASU 2015-11, “Simplifying the Measurement of Inventory". The ASU provides guidance for the subsequent measurement of inventory and requires that inventory that is measured using average cost be measured at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The ASU was effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The implementation of this update did not materially impact the Company’s consolidated financial position, results of operations or cash flows or disclosure. Employee Share-Based Payment Accounting In March 2016, the FASB issued ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting ". This ASU simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for forfeitures, income taxes, and statutory tax withholding requirements. The ASU was effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. The Company elected to continue to estimate the total number of awards for which the requisite service period will not be rendered. The implementation of this update did not impact the Company’s consolidated financial position, results of operations or cash flows or disclosure. Income Taxes - Intra-Entity Transfers of Assets Other than Inventory At December 31, 2016, GAAP prohibited the recognition of current and deferred income taxes for intra-entity transfers until an asset leaves the consolidated group, therefore, the current income tax effect of tax reorganizations completed in 2016 was deferred and recognized as prepaid income taxes. At December 31, 2016, the Company's balance sheet included $54.1 million of prepaid income taxes, $12.3 million in current prepaid taxes and $41.8 million in long-term prepaid taxes, and $37.5 million of current income taxes payable relating to tax reorganizations completed in 2016. In October 2016, the FASB issued ASU 2016-16, "Intra-Entity Transfers of Assets Other than Inventory." This ASU requires companies to recognize the income tax effects of intercompany sales or transfers of assets, other than inventory, in the income statement as income tax expense or benefit in the period the sale or transfer occurs. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those years. Early adoption was permitted as of the beginning of an annual reporting period. The ASU is required to be applied on a modified retrospective basis with a cumulative-effect adjustment directly to retained earnings in the period of adoption. The Company early adopted this ASU on January 1, 2017, and in the three months ending March 31, 2017, wrote off the income tax effects that had been deferred from past intercompany transactions to opening deficit. Prepaid tax of $54.1 million and deferred tax assets of $178.6 million were recorded directly to opening deficit at January 1, 2017. Deferred tax assets recorded upon adoption were assessed for realizability under Accounting Standards Codification ("ASC") 740 "Income Taxes", and, valuation allowances were recognized on those deferred tax assets as necessary on the date of adoption. The adoption of ASU 2016-16 did not have any effect on the Company’s cash flows. Restricted Cash and Cash Equivalents In November 2016, the FASB issued ASU 2016-18, "Restricted Cash". ASU 2016-18 requires that a statement of cash flows explain the change during the period in the total cash, cash equivalents and amounts generally described as restricted cash or restricted cash equivalents. ASU 2016-18 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2017. Early adoption was permitted. The Company early adopted this ASU on January 1, 2017, on a retrospective basis to each period presented. The implementation of this ASU did not impact the Company's consolidated financial position or results of operations. For the nine months ended September 30, 2016 , the net decrease in cash, cash equivalents and restricted cash and cash equivalents currently disclosed was $77.5 million , compared with the net decrease in cash and cash equivalents of $97.3 million as previously disclosed in the consolidated statement of cash flows prior to the adoption of ASU 2016-18. Clarifying the Definition of a Business In January 2017, the FASB issued ASU 2017-01, "Clarifying the Definition of a Business". ASU 2017-01 narrows the definition of a business and provides a framework that gives entities a basis for making reasonable judgments about whether a transaction involves an asset or a business. ASU 2017-01 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2017. Early adoption was permitted and the Company adopted this ASU on January 1, 2017. The Company now applies an initial screen for determining whether a transaction involves an asset or a business. When substantially all of the fair value of the gross assets acquired is concentrated in a single identified asset, or group of similar identifiable assets, the set will not be a business and no goodwill or gain on acquisition will be recognized. If the screen is not met, a set cannot be considered a business unless it includes an input and a substantive process that together significantly contribute to the ability to create an output. The Company’s acquisition of the Santana and Nancy Burdine-Maxine oil and gas properties in the nine months ended September 30, 2017 was not considered a business under this ASU and therefore not allocated goodwill or gain on acquisition (Note 4). Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU 2017-04, "Simplifying the Test for Goodwill Impairment". ASU 2017-04 eliminates step 2 of the goodwill impairment test. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. ASU 2017-04 is effective for annual reporting periods and interim reporting periods within those annual reporting periods, beginning after December 15, 2019. Early adoption is permitted. At September 30, 2017 , the Company performed a qualitative assessment of goodwill and, based on this assessment, no impairment of goodwill was identified. The Company did not have to perform step 2 of the goodwill impairment test. Recently Issued Accounting Pronouncements Revenue from Contracts with Customers In May 2014, the FASB issued guidance regarding the accounting for revenue from contracts with customers. In August 2015, the FASB issued ASU 2015-14, “Revenue from Contracts with Customers - Deferral of the Effective Date". The ASU deferred the effective date of the new revenue recognition model by one year. As a result, the guidance will be effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. In March 2016, the FASB issued ASU 2016-08, “Principal versus Agent Considerations (Reporting Revenue Gross versus Net)" which clarifies implementation guidance on principal versus agent considerations. In April, May and December 2016, the FASB issued ASU 2016-10, “Identifying Performance Obligations and Licensing", ASU 2016-12, “Narrow-Scope Improvements and Practical Expedients" and ASU 2016-20 "Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers", respectively, which addressed implementation issues and provided technical corrections. The guidance may be applied retrospectively or using a modified retrospective approach to adjust retained earnings. The Company is continuing to evaluate the impact of the ASU and currently expects that the standard will not have a material impact on the Company’s consolidated financial statements other than enhanced disclosures related to revenues from contracts with customers. The Company intends to adopt the new standard using the modified retrospective method at the date of adoption, which is expected to be January 1, 2018.

Segment and Geographic Report19

Segment and Geographic Reporting (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Information on Reportable Segments and Other Activities	The following tables present information on the Company’s reportable segments and other activities: Three Months Ended September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 103,768 $ — $ — $ — $ 103,768 Depletion, depreciation and accretion 33,388 881 — 223 34,492 Asset impairment — 176 — 611 787 General and administrative expenses 5,500 301 — 2,850 8,651 Income (loss) before income taxes 31,276 (1,405 ) — (8,648 ) 21,223 Segment capital expenditures 70,606 998 — 90 71,694 Three Months Ended September 30, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 65,944 $ — $ 2,595 $ — $ 68,539 Depletion, depreciation and accretion 34,156 206 1,022 345 35,729 Asset impairment 298,370 — 21,604 — 319,974 General and administrative expenses 1,921 218 218 3,235 5,592 Loss before income taxes (299,306 ) (768 ) (20,977 ) (15,140 ) (336,191 ) Segment capital expenditures 20,476 1,360 3,102 142 25,080 Nine Months Ended September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 286,137 $ — $ 8,418 $ — $ 294,555 Depletion, depreciation and accretion 88,453 1,350 2,263 663 92,729 Asset impairment — 628 — 611 1,239 General and administrative expenses 15,561 974 743 9,598 26,876 Income (loss) before income taxes 90,018 (2,685 ) 3,369 (31,422 ) 59,280 Segment capital expenditures 168,881 3,207 2,811 820 175,719 Nine Months Ended September 30, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Oil and natural gas sales $ 191,515 $ — $ 6,140 $ — $ 197,655 Depletion, depreciation and accretion 100,350 418 2,764 993 104,525 Asset impairment 431,810 899 37,006 — 469,715 General and administrative expenses 9,614 1,014 751 9,235 20,614 Loss before income taxes (436,863 ) (2,224 ) (36,523 ) (17,122 ) (492,732 ) Segment capital expenditures 56,997 3,730 7,982 958 69,667
Schedule of Long-lived Assets by Geographical Area	As at September 30, 2017 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Property, plant and equipment $ 1,054,136 $ 70,903 $ — $ 2,585 $ 1,127,624 Goodwill 102,581 — — — 102,581 All other assets 176,672 11,103 — 5,196 192,971 Total Assets $ 1,333,389 $ 82,006 $ — $ 7,781 $ 1,423,176 As at December 31, 2016 (Thousands of U.S. Dollars) Colombia Peru Brazil All Other Total Property, plant and equipment $ 939,947 $ 68,428 $ 55,196 $ 3,038 $ 1,066,609 Goodwill 102,581 — — — 102,581 All other assets 177,393 10,848 1,619 8,846 198,706 Total Assets $ 1,219,921 $ 79,276 $ 56,815 $ 11,884 $ 1,367,896

Property, Plant and Equipment20

Property, Plant and Equipment and Inventory (Tables)	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, Plant and Equipment (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Oil and natural gas properties Proved $ 2,836,263 $ 2,652,171 Unproved 613,419 647,774 3,449,682 3,299,945 Other 27,236 29,445 3,476,918 3,329,390 Accumulated depletion, depreciation and impairment (2,349,294 ) (2,262,781 ) $ 1,127,624 $ 1,066,609
Schedule of Asset Impairment	Asset impairment for the three and nine months ended September 30, 2017 , and 2016 was as follows: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Impairment of oil and gas properties $ 787 $ 319,974 $ 1,239 $ 469,051 Impairment of inventory — — — 664 $ 787 $ 319,974 $ 1,239 $ 469,715
Schedule of the Allocation of the Cost of the Acquisition	The following table shows the allocation of the cost of the acquisition based on the relative fair values of the assets and liabilities acquired: (Thousands of U.S. Dollars) Cost of asset acquisition: Cash $ 30,410 Allocation of Consideration Paid: Oil and gas properties Proved $ 24,405 Unproved 8,649 33,054 Inventory 869 Asset retirement obligation - long-term (3,513 ) $ 30,410
Schedule of Assets and Liabilities of the Brazil Business Unit	At December 31, 2016, assets and liabilities of the Brazil business unit were as follows: (Thousands of U.S. Dollars) As at December 31, 2016 Current assets $ 1,634 Property, plant and equipment 55,376 $ 57,010 Current liabilities $ (11,590 ) Long-term liabilities (2,297 ) $ (13,887 )

Debt and Interest Expense (Tabl

Debt and Interest Expense (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Debt	The Company's debt at September 30, 2017 , and December 31, 2016 , was as follows: (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Convertible senior notes $ 115,000 $ 115,000 Revolving credit facility 120,000 90,000 Unamortized debt issuance costs (5,785 ) (7,917 ) Long-term debt $ 229,215 $ 197,083
Schedule of Interest Expense Recognized	The following table presents total interest expense recognized in the accompanying interim unaudited condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Contractual interest and other financing expenses $ 3,346 $ 2,938 $ 8,547 $ 5,029 Amortization of debt issuance costs 643 2,184 1,868 2,813 $ 3,989 $ 5,122 $ 10,415 $ 7,842

Share Capital (Tables)

Share Capital (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Common Stock	Shares of Common Stock Exchangeable Shares of Gran Tierra Exchangeco Inc. Exchangeable Shares of Gran Tierra Goldstrike Inc. Balance, December 31, 2016 390,807,194 4,812,592 3,387,302 Shares repurchased and canceled (4,235,890 ) — — Exchange of exchangeable shares 301,230 (142,500 ) (158,730 ) Shares canceled (4 ) — — Balance, September 30, 2017 386,872,530 4,670,092 3,228,572
Schedule of PSU, DSU, RSU and Stock Option Activity	The following table provides information about p erformance stock units (“PSUs”), deferred share units (“DSUs”), restricted stock units (“RSUs”) and stock option activity for the nine months ended September 30, 2017 : PSUs DSUs RSUs Stock Options Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Share Units Number of Outstanding Stock Options Weighted Average Exercise Price/Stock Option ($) Balance, December 31, 2016 3,362,717 208,698 359,145 9,239,478 4.16 Granted 3,229,620 171,388 — 1,964,156 2.54 Exercised — — (211,022 ) — — Forfeited (641,159 ) — (9,402 ) (903,910 ) (4.81 ) Expired — — — (1,396,667 ) (4.65 ) Balance, September 30, 2017 5,951,178 380,086 138,721 8,903,057 3.66
Schedule of Weighted Average Shares Outstanding	Weighted Average Shares Outstanding Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Weighted average number of common and exchangeable shares outstanding 394,771,194 321,725,379 397,439,007 304,098,944 Shares issuable pursuant to stock options 61,325 — 187,150 — Shares assumed to be purchased from proceeds of stock options (57,566 ) — (175,520 ) — Weighted average number of diluted common and exchangeable shares outstanding 394,774,953 321,725,379 397,450,637 304,098,944

Asset Retirement Obligation (Ta

Asset Retirement Obligation (Tables)	9 Months Ended
	Sep. 30, 2017
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in the Carrying Amounts of the Asset Retirement Obligation	Changes in the carrying amounts of the asset retirement obligation associated with the Company’s oil and natural gas properties were as follows: Nine Months Ended Year Ended (Thousands of U.S. Dollars) September 30, 2017 December 31, 2016 Balance, beginning of period $ 43,357 $ 33,224 Liability incurred 2,942 2,606 Liabilities assumed in acquisition 3,513 15,723 Accretion 3,101 2,789 Settlements (1,039 ) (872 ) Liabilities associated with assets sold (2,200 ) (3,257 ) Revisions in estimated liability (5,670 ) (6,856 ) Balance, end of period $ 44,004 $ 43,357 Asset retirement obligation - current $ 355 $ 5,215 Asset retirement obligation - long-term 43,649 38,142 $ 44,004 $ 43,357

Financial Instruments and Fai24

Financial Instruments and Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Derivatives and RSU, PSU and DSU Liabilities	The fair value of derivatives and RSU, PSU and DSU liabilities at September 30, 2017 , and December 31, 2016 , were as follows: (Thousands of U.S. Dollars) As at September 30, 2017 As at December 31, 2016 Foreign currency derivative asset $ 512 $ 578 Commodity price derivative liability $ 65 $ 3,824 RSU, PSU and DSU liability 6,851 3,907 $ 6,916 $ 7,731
Schedule of Gains or Losses on Financial Instruments Recognized	The following table presents gains or losses on financial instruments recognized in the accompanying interim unaudited condensed consolidated statements of operations: Three Months Ended September 30, Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 2017 2016 Commodity price derivative loss (gain) $ 2,489 $ 2,190 $ (3,759 ) $ 856 Foreign currency derivatives gain (814 ) (840 ) (1,452 ) (1,958 ) Trading securities loss — 701 — 2,926 Financial instruments loss (gain) $ 1,675 $ 2,051 $ (5,211 ) $ 1,824
Schedule of Commodity Price Derivative Positions and Commodity Foreign Currency Contracts	At September 30, 2017 , the Company had outstanding commodity price derivative positions as follows: Period and type of instrument Volume, Reference Sold Put ($/bbl) Purchased Put Sold Call ($/bbl) Collar: October 1, 2016 to December 31, 2017 5,000 ICE Brent $ 35 $ 45 $ 65 Collar: June 1, 2017 to December 31, 2017 10,000 ICE Brent $ 35 $ 45 $ 65 Subsequent to September 30, 2017, the Company entered into the following commodity price contracts: Period and type of instrument Volume, Reference Purchased Swap Purchased Call ($/bbl) Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 55.75 Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 56.05 Participating Swap: January 1, to December 31, 2018 2,500 ICE Brent $ 50.00 $ 54.10
Schedule of Outstanding Foreign Currency Derivative Positions	At September 30, 2017 , the Company had outstanding foreign currency derivative positions as follows: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (1) (Thousands of U.S. Dollars) Reference Purchased Call Sold Put Collar: October 1, 2017 to October 31, 2017 23,000 7,832 COP 3,000 3,117 Collar: November 1, 2017 to November 30, 2017 25,000 8,513 COP 3,000 3,139 Collar: December 1, 2017 to December 28, 2017 25,000 8,513 COP 3,000 3,142 73,000 24,858 (1) At September 30, 2017 foreign exchange rate. Subsequent to September 30, 2017, the Company entered into the following foreign currency contracts: Period and type of instrument Amount Hedged U.S. Dollar Equivalent of Amount Hedged (1) (Thousands of U.S. Dollars) Reference Purchased Call Sold Put Collar: January 1, 2018 to December 31, 2018 132,000 44,949 COP 3,000 3,112 (1) At September 30, 2017 foreign exchange rate.

Supplemental Cash Flow Inform25

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Reconciliation of Cash, Cash Equivalents and Restricted Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash and cash equivalents with the Company's interim unaudited condensed consolidated balance sheet that sum to the total of the same such amounts shown in the interim unaudited condensed consolidated statements of cash flows: (Thousands of U.S. Dollars) As at September 30, As at December 31, 2017 2016 2016 2015 Cash and cash equivalents $ 15,125 $ 48,073 $ 25,175 $ 145,342 Restricted cash and cash equivalents - current 3,920 13,198 8,322 92 Restricted cash and cash equivalents - long-term 10,332 9,993 9,770 3,317 $ 29,377 $ 71,264 $ 43,267 $ 148,751
Schedule of Net Changes in Assets and Liabilities	Net changes in assets and liabilities from operating activities were as follows: Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 Accounts receivable and other long-term assets $ 8,356 $ 15,233 Derivatives — (4,563 ) Inventory (28 ) 3,630 Prepaids 3,080 1,864 Accounts payable and accrued and other long-term liabilities 5,951 (11,297 ) Taxes receivable and payable (45,464 ) 13,230 Net changes in assets and liabilities from operating activities $ (28,105 ) $ 18,097
Schedule of Additional Supplemental Cash Flow Disclosures	The following table provides additional supplemental cash flow disclosures: Nine Months Ended September 30, (Thousands of U.S. Dollars) 2017 2016 Non-cash investing activities: Net liabilities related to property, plant and equipment, end of period $ 68,018 $ 27,520

Significant Accounting Polici26

Significant Accounting Policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid income taxes			$ 54,100
Current prepaid taxes	$ 0		12,271
Long-term prepaid taxes	0		41,784
Current income taxes payable			37,500
Net decrease in cash, cash equivalents and restricted cash and cash equivalents	$ 13,890	$ 77,487
Previously disclosed
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net decrease in cash and cash equivalents		$ 97,300
Opening deficit | New Accounting Pronouncement, Early Adoption, Effect | ASU 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid income taxes			54,100
Deferred tax assets			$ 178,600

Segment and Geographic Report27

Segment and Geographic Reporting - Schedule of Information on Reportable Segments and Other Activities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Oil and natural gas sales	$ 103,768	$ 68,539	$ 294,555	$ 197,655
Depletion, depreciation and accretion	34,492	35,729	92,729	104,525
Asset impairment	787	319,974	1,239	469,715
General and administrative expenses	8,651	5,592	26,876	20,614
Income (loss) before income taxes	21,223	(336,191)	59,280	(492,732)
Segment capital expenditures	71,694	25,080	175,719	69,667
Reportable Segments | Colombia
Segment Reporting Information [Line Items]
Oil and natural gas sales	103,768	65,944	286,137	191,515
Depletion, depreciation and accretion	33,388	34,156	88,453	100,350
Asset impairment	0	298,370	0	431,810
General and administrative expenses	5,500	1,921	15,561	9,614
Income (loss) before income taxes	31,276	(299,306)	90,018	(436,863)
Segment capital expenditures	70,606	20,476	168,881	56,997
Reportable Segments | Peru
Segment Reporting Information [Line Items]
Oil and natural gas sales	0	0	0	0
Depletion, depreciation and accretion	881	206	1,350	418
Asset impairment	176	0	628	899
General and administrative expenses	301	218	974	1,014
Income (loss) before income taxes	(1,405)	(768)	(2,685)	(2,224)
Segment capital expenditures	998	1,360	3,207	3,730
Reportable Segments | Brazil
Segment Reporting Information [Line Items]
Oil and natural gas sales	0	2,595	8,418	6,140
Depletion, depreciation and accretion	0	1,022	2,263	2,764
Asset impairment	0	21,604	0	37,006
General and administrative expenses	0	218	743	751
Income (loss) before income taxes	0	(20,977)	3,369	(36,523)
Segment capital expenditures	0	3,102	2,811	7,982
All Other
Segment Reporting Information [Line Items]
Oil and natural gas sales	0	0	0	0
Depletion, depreciation and accretion	223	345	663	993
Asset impairment	611	0	611	0
General and administrative expenses	2,850	3,235	9,598	9,235
Income (loss) before income taxes	(8,648)	(15,140)	(31,422)	(17,122)
Segment capital expenditures	$ 90	$ 142	$ 820	$ 958

Segment and Geographic Report28

Segment and Geographic Reporting - Schedule of Long-lived Assets by Geographical Area (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property, plant and equipment	$ 1,127,624	$ 1,066,609
Goodwill	102,581	102,581
All other assets	192,971	198,706
Total Assets	1,423,176	1,367,896
Reportable Segments | Colombia
Segment Reporting Information [Line Items]
Property, plant and equipment	1,054,136	939,947
Goodwill	102,581	102,581
All other assets	176,672	177,393
Total Assets	1,333,389	1,219,921
Reportable Segments | Peru
Segment Reporting Information [Line Items]
Property, plant and equipment	70,903	68,428
Goodwill	0	0
All other assets	11,103	10,848
Total Assets	82,006	79,276
Reportable Segments | Brazil
Segment Reporting Information [Line Items]
Property, plant and equipment	0	55,196
Goodwill	0	0
All other assets	0	1,619
Total Assets	0	56,815
All Other
Segment Reporting Information [Line Items]
Property, plant and equipment	2,585	3,038
Goodwill	0	0
All other assets	5,196	8,846
Total Assets	$ 7,781	$ 11,884

Property, Plant and Equipment29

Property, Plant and Equipment and Inventory - Schedule of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Oil and natural gas properties	$ 3,476,918	$ 3,329,390
Accumulated depletion, depreciation and impairment	(2,349,294)	(2,262,781)
Total Property, Plant and Equipment (Notes 3 and 4)	1,127,624	1,066,609
Oil and natural gas properties
Property, Plant and Equipment [Line Items]
Oil and natural gas properties	3,449,682	3,299,945
Proved
Property, Plant and Equipment [Line Items]
Oil and natural gas properties	2,836,263	2,652,171
Unproved
Property, Plant and Equipment [Line Items]
Oil and natural gas properties	613,419	647,774
Other
Property, Plant and Equipment [Line Items]
Oil and natural gas properties	$ 27,236	$ 29,445

Property, Plant and Equipment30

Property, Plant and Equipment and Inventory - Schedule of Asset Impairment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Impairment of oil and gas properties	$ 787,000	$ 319,974,000	$ 1,239,000	$ 469,051,000
Impairment of inventory	0	0	0	664,000
Total asset impairment	$ 787,000	$ 319,974,000	$ 1,239,000	$ 469,715,000

Property, Plant and Equipment31

Property, Plant and Equipment and Inventory - Property, Plant and Equipment (Narrative) (Details) - $ / bbl	3 Months Ended								9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Crude Oil and NGL
Property, Plant and Equipment [Line Items]
Average Brent price per bbl (in dollars per barrel)	52.70	51.35	49.33	42.92	42.23	44.48	48.79	54.08
Assets | Oil and natural gas properties | Full cost method
Property, Plant and Equipment [Line Items]
Discount rate									10.00%

Property, Plant and Equipment32

Property, Plant and Equipment and Inventory - Acquisition of Santana and Nancy Burdine-Maxine Blocks (Narrative) (Details) $ in Thousands	Apr. 27, 2017USD ($)
Property, Plant and Equipment [Abstract]
Cash consideration paid for acquisition	$ 30,410

Property, Plant and Equipment33

Property, Plant and Equipment and Inventory - Schedule of the Allocation of the Cost of the Acquisition (Details) $ in Thousands	Apr. 27, 2017USD ($)
Cost of asset acquisition:
Cash	$ 30,410
Oil and gas properties
Proved	24,405
Unproved	8,649
Total oil and gas properties	33,054
Inventory	869
Asset retirement obligation - long-term	(3,513)
Consideration paid	$ 30,410

Property, Plant and Equipment34

Property, Plant and Equipment and Inventory - Disposition of Brazil Business Unit (Narrative) (Details) $ in Thousands	Jun. 30, 2017USD ($)subsidiary	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of Brazil business unit		$ 0	$ 0	$ 9,076	$ 0
Cash payment from the purchaser				$ 4,700	$ 0
Brazil Divestiture | Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of indirect subsidiaries through which the Company completed the disposition of its assets in Brazil | subsidiary	2
Purchase price for disposition of Brazil business unit	$ 35,000
Loss on sale of Brazil business unit	9,100
Cash payment from the purchaser	4,700
Selling Subsidiaries | Brazil Divestiture | Disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration paid to the Selling Subsidiaries	$ 38,000

Property, Plant and Equipment35

Property, Plant and Equipment and Inventory - Schedule of Assets and Liabilities of the Brazil Business Unit (Details) - Brazil Divestiture - Disposed of by sale $ in Thousands	Dec. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets	$ 1,634
Property, plant and equipment	55,376
Total assets	57,010
Current liabilities	(11,590)
Long-term liabilities	(2,297)
Total liabilities	$ (13,887)

Property, Plant and Equipment36

Property, Plant and Equipment and Inventory - Inventory (Narrative) (Details) bbl in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)bbl	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)bbl	Sep. 30, 2016USD ($)	Dec. 31, 2016USD ($)bbl
Property, Plant and Equipment [Abstract]
Oil inventories	$ 4,500,000		$ 4,500,000		$ 6,000,000
Supplies inventories	$ 2,500,000		$ 2,500,000		$ 1,800,000
Oil inventory (in barrels) | bbl	168		168		208
Oil inventory impairment related to lower oil prices	$ 0	$ 0	$ 0	$ 664,000

Debt and Interest Expense - Nar

Debt and Interest Expense - Narrative (Details) - USD ($)	Sep. 30, 2017	Jun. 01, 2017	May 31, 2017
Revolving credit facility
Line of Credit Facility [Line Items]
Borrowing base	$ 300,000,000	$ 300,000,000	$ 250,000,000

Debt and Interest Expense - Sch

Debt and Interest Expense - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (5,785)	$ (7,917)
Long-term debt	229,215	197,083
Convertible senior notes
Debt Instrument [Line Items]
Convertible senior notes and revolving credit facility	115,000	115,000
Revolving credit facility | Revolving credit facility
Debt Instrument [Line Items]
Convertible senior notes and revolving credit facility	$ 120,000	$ 90,000

Debt and Interest Expense - S39

Debt and Interest Expense - Schedule of Interest Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 1,868	$ 2,813
Total interest expense recognized	$ 3,989	$ 5,122	10,415	7,842
Convertible senior notes
Debt Instrument [Line Items]
Contractual interest and other financing expenses	3,346	2,938	8,547	5,029
Amortization of debt issuance costs	643	2,184	1,868	2,813
Total interest expense recognized	$ 3,989	$ 5,122	$ 10,415	$ 7,842

Share Capital - Additional Info

Share Capital - Additional Information (Narrative) (Details) - $ / shares	Jan. 27, 2017	Sep. 30, 2017	Feb. 06, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Authorized share capital (in shares)		595,000,002
Authorized share capital, Common Stock (in shares)		570,000,000
Common Stock, par value (in dollars per share)		$ 0.001		$ 0.001
Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized share capital, Preferred Stock (in shares)		25,000,000
Preferred Stock, par value (in dollars per share)		$ 0.001
Special A Voting Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized share capital, Preferred Stock (in shares)		1
Preferred Stock, par value (in dollars per share)		$ 0.001
Special B Voting Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized share capital, Preferred Stock (in shares)		1
Preferred Stock, par value (in dollars per share)		$ 0.001
The 2017 Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under the 2017 Program (up to) (in shares)			19,540,359
Shares authorized representing issued and outstanding shares of Common Stock (as a percent)	5.00%

Share Capital - Schedule of Com

Share Capital - Schedule of Common Stock (Details)	9 Months Ended
	Sep. 30, 2017shares
Increase (Decrease) in Common Stock
Beginning balance (in shares)	390,807,194
Ending balance (in shares)	386,872,530
Shares of Common Stock
Increase (Decrease) in Common Stock
Beginning balance (in shares)	390,807,194
Shares repurchased and canceled (in shares)	(4,235,890)
Exchange of exchangeable shares (in shares)	301,230
Shares canceled (in shares)	(4)
Ending balance (in shares)	386,872,530
Shares of Common Stock | Exchangeable Shares of Gran Tierra Exchangeco Inc.
Increase (Decrease) in Common Stock
Beginning balance (in shares)	4,812,592
Shares repurchased and canceled (in shares)	0
Exchange of exchangeable shares (in shares)	(142,500)
Shares canceled (in shares)	0
Ending balance (in shares)	4,670,092
Shares of Common Stock | Exchangeable Shares of Gran Tierra Goldstrike Inc.
Increase (Decrease) in Common Stock
Beginning balance (in shares)	3,387,302
Shares repurchased and canceled (in shares)	0
Exchange of exchangeable shares (in shares)	(158,730)
Shares canceled (in shares)	0
Ending balance (in shares)	3,228,572

Share Capital - Schedule of PSU

Share Capital - Schedule of PSU, DSU, RSU and Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Number of Outstanding Stock Options
Beginning Balance (in shares)	9,239,478
Granted (in shares)	1,964,156
Exercised (in shares)	0
Forfeited (in shares)	(903,910)
Expired (in shares)	(1,396,667)
Ending Balance (in shares)	8,903,057
Weighted Average Exercise Price/Stock Option ($)
Beginning balance (in dollars per share) | $ / shares	$ 4.16
Granted (in dollars per share) | $ / shares	2.54
Exercised (in dollars per share) | $ / shares	0
Forfeited (in dollars per share) | $ / shares	(4.81)
Expired (in dollars per share) | $ / shares	(4.65)
Ending balance (in dollars per share) | $ / shares	$ 3.66
PSUs
Number of Outstanding Share Units
Beginning Balance (in shares)	3,362,717
Granted (in shares)	3,229,620
Exercised (in shares)	0
Forfeited (in shares)	(641,159)
Expired (in shares)	0
Ending Balance (in shares)	5,951,178
DSUs
Number of Outstanding Share Units
Beginning Balance (in shares)	208,698
Granted (in shares)	171,388
Exercised (in shares)	0
Forfeited (in shares)	0
Expired (in shares)	0
Ending Balance (in shares)	380,086
RSUs
Number of Outstanding Share Units
Beginning Balance (in shares)	359,145
Granted (in shares)	0
Exercised (in shares)	(211,022)
Forfeited (in shares)	(9,402)
Expired (in shares)	0
Ending Balance (in shares)	138,721

Share Capital - Equity Compensa

Share Capital - Equity Compensation Awards (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 11.5		$ 11.5		$ 10
Weighted average period for recognition			1 year 8 months 26 days
General and administrative (G&A) expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1.8	$ 0.9	$ 4.9	$ 4.4

Share Capital - Schedule of Wei

Share Capital - Schedule of Weighted Average Shares Outstanding (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average number of common and exchangeable shares outstanding (in shares)	394,771,194	321,725,379	397,439,007	304,098,944
Shares issuable pursuant to stock options (in shares)	61,325	0	187,150	0
Shares assumed to be purchased from proceeds of stock options (in shares)	(57,566)	0	(175,520)	0
Weighted average number of diluted common and exchangeable shares outstanding (in shares)	394,774,953	321,725,379	397,450,637	304,098,944

Share Capital - Weighted Averag

Share Capital - Weighted Average Shares Outstanding (Narrative) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Convertible senior notes | Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stated interest rate	5.00%		5.00%
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options excluded from diluted income (loss) per share calculation (in shares)	9,259,811	9,084,162	9,744,747	11,155,962

Asset Retirement Obligation - S

Asset Retirement Obligation - Schedule of Changes in the Carrying Amounts of the Asset Retirement Obligation (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis
Balance, beginning of period	$ 43,357	$ 33,224
Liability incurred	2,942	2,606
Liabilities assumed in acquisition	3,513	15,723
Accretion	3,101	2,789
Settlements	(1,039)	(872)
Liabilities associated with assets sold	(2,200)	(3,257)
Revisions in estimated liability	(5,670)	(6,856)
Balance, end of period	44,004	43,357
Asset retirement obligation - current			$ 355	$ 5,215
Asset retirement obligation - long-term			43,649	38,142
Asset retirement obligation	$ 43,357	$ 33,224	$ 44,004	$ 43,357

Asset Retirement Obligation - N

Asset Retirement Obligation - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]
Cash payments included in settlements	$ 462	$ 496
Fair value of assets that are legally restricted	$ 12,600		$ 12,000

Taxes (Details)

Taxes (Details)	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	85.00%	31.00%
U.S. statutory rate	35.00%

Contingencies (Details)

Contingencies (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Letters of credit and other credit support provided	$ 74,500,000	$ 96,800,000
Pending Litigation Royalty, Transportation and Related Costs
Loss Contingencies [Line Items]
Estimated compensation which would be payable if the ANH's interpretation is correct	49,800,000
Amount accrued	$ 0

Financial Instruments and Fai50

Financial Instruments and Fair Value Measurement - Schedule of Fair Value of Derivatives and RSU, PSU and DSU Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative asset	$ 512	$ 578
RSU, PSU and DSU liability	6,851	3,907
Liabilities, fair value disclosure	6,916	7,731
Foreign currency derivative asset
Derivatives, Fair Value [Line Items]
Derivative asset	512	578
Commodity Hedge
Derivatives, Fair Value [Line Items]
Commodity price derivative liability	$ 65	$ 3,824

Financial Instruments and Fai51

Financial Instruments and Fair Value Measurement - Schedule of Gains or Losses on Financial Instruments Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Trading securities loss	$ 0	$ 701	$ 0	$ 2,926
Financial instruments loss (gain)	1,675	2,051	(5,211)	1,824
Commodity price derivative loss (gain)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative (loss) gain	2,489	2,190	(3,759)	856
Foreign currency derivatives gain
Derivative Instruments, Gain (Loss) [Line Items]
Derivative (loss) gain	$ (814)	$ (840)	$ (1,452)	$ (1,958)

Financial Instruments and Fai52

Financial Instruments and Fair Value Measurement - Narrative (Details) $ in Millions	Sep. 30, 2017USD ($)
Carrying amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of the Notes	$ 110.7
Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Value of the Notes	$ 121.9

Financial Instruments and Fai53

Financial Instruments and Fair Value Measurement - Schedule of Commodity Price Derivative Positions and Commodity Foreign Currency Contracts (Details) - Commodity Hedge	1 Months Ended	9 Months Ended
	Nov. 02, 2017$ / bblbbl	Sep. 30, 2017$ / bblbbl
Collar: October 1, 2016 to December 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl		5,000
Collar: October 1, 2016 to December 31, 2017 | Sold | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)		35
Collar: October 1, 2016 to December 31, 2017 | Sold | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cap price (in dollars per barrel)		65
Collar: October 1, 2016 to December 31, 2017 | Purchased | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)		45
Collar: June 1, 2017 to December 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl		10,000
Collar: June 1, 2017 to December 31, 2017 | Sold | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)		35
Collar: June 1, 2017 to December 31, 2017 | Sold | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cap price (in dollars per barrel)		65
Collar: June 1, 2017 to December 31, 2017 | Purchased | Put
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)		45
Subsequent Event | Swap: January 1, to December 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl	2,500
Subsequent Event | Swap: January 1, to December 31, 2018 | Purchased | Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)	55.75
Subsequent Event | Swap: January 1, to December 31, 2018 | Purchased | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)
Subsequent Event | Swap: January 1, to December 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl	2,500
Subsequent Event | Swap: January 1, to December 31, 2018 | Purchased | Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)	56.05
Subsequent Event | Participating Swap: January 1, to December 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Volume (in barrels of oil per day) | bbl	2,500
Subsequent Event | Participating Swap: January 1, to December 31, 2018 | Purchased | Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)	50
Subsequent Event | Participating Swap: January 1, to December 31, 2018 | Purchased | Call
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor price (in dollars per barrel)	54.10

Financial Instruments and Fai54

Financial Instruments and Fair Value Measurement - Schedule of Outstanding Foreign Currency Derivative Positions (Details) $ in Thousands, COP in Millions	Nov. 02, 2017COPCOP / collar	Nov. 02, 2017USD ($)COP / collar	Sep. 30, 2017COPCOP / collar	Sep. 30, 2017USD ($)COP / collar
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount Hedged			COP 73,000	$ 24,858
Collar: October 1, 2017 to October 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount Hedged			23,000	7,832
Collar: November 1, 2017 to November 30, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount Hedged			25,000	8,513
Collar: December 1, 2017 to December 28, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount Hedged			COP 25,000	$ 8,513
Collar: January 1, 2018 to December 31, 2018 | Subsequent Event
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount Hedged	COP 132,000	$ 44,949
Purchased | Call | Collar: October 1, 2017 to October 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Purchased Call (in COP per collar)			3,000	3,000
Purchased | Call | Collar: November 1, 2017 to November 30, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Purchased Call (in COP per collar)			3,000	3,000
Purchased | Call | Collar: December 1, 2017 to December 28, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Purchased Call (in COP per collar)			3,000	3,000
Purchased | Call | Collar: January 1, 2018 to December 31, 2018 | Subsequent Event
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Purchased Call (in COP per collar)	3,000	3,000
Sold | Put | Collar: October 1, 2017 to October 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sold Put (in COP per collar)			3,117	3,117
Sold | Put | Collar: November 1, 2017 to November 30, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sold Put (in COP per collar)			3,139	3,139
Sold | Put | Collar: December 1, 2017 to December 28, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sold Put (in COP per collar)			3,142	3,142
Sold | Put | Collar: January 1, 2018 to December 31, 2018 | Subsequent Event
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sold Put (in COP per collar)	3,112	3,112

Supplemental Cash Flow Inform55

Supplemental Cash Flow Information - Reconciliation of Cash, Cash Equivalents and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 15,125	$ 25,175	$ 48,073	$ 145,342
Restricted cash and cash equivalents - current	3,920	8,322	13,198	92
Restricted cash and cash equivalents - long-term	10,332	9,770	9,993	3,317
Cash, cash equivalents and restricted cash and cash equivalents	$ 29,377	$ 43,267	$ 71,264	$ 148,751

Supplemental Cash Flow Inform56

Supplemental Cash Flow Information - Schedule of Net Changes in Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Accounts receivable and other long-term assets	$ 8,356	$ 15,233
Derivatives	0	(4,563)
Inventory	(28)	3,630
Prepaids	3,080	1,864
Accounts payable and accrued and other long-term liabilities	5,951	(11,297)
Taxes receivable and payable	(45,464)	13,230
Net changes in assets and liabilities from operating activities	$ (28,105)	$ 18,097

Supplemental Cash Flow Inform57

Supplemental Cash Flow Information - Schedule of Additional Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Net liabilities related to property, plant and equipment, end of period	$ 68,018	$ 27,520