Income and mining taxes (Tables)

12 Months Ended

Dec. 31, 2017

Statement [Line Items]

Disclosure of detailed information about effective income tax expense recovery [Table Text Block]

		Year ended
		December 31,
		2017			2016
Current:
Income taxes
Canada	$	5,970		$	7,000
Peru		24,523			-
Mining Taxes
Canada		4,744			1,309
Peru		14,706			8,971
		49,943			17,280
Deferred:
Income taxes (recoveries) - origination, revaluation and/or reversal of temporary differences
Canada		2,636			(24,013	)
Peru		30,721			39,350
United States		(46,908	)		5,617
Mining taxes (recoveries) - origination, revaluation and/or reversal of temporary differences
Canada		467			3,739
Peru		(613	)		(1,441	)
Adjustments in respect of prior years		(1,417	)		266
		(15,114	)		23,518
	$	34,829		$	40,798

Disclosure of deferred taxes [Table Text Block]

		Dec. 31, 2017			Dec. 31, 2016
Deferred income tax asset
Canada	$	35,989		$	79,483
Deferred income tax liability
Canada		-			(34,379	)
Peru		(177,519	)		(149,351	)
United States		(107,691	)		(154,600	)
Deferred mining tax liability:
Canada		(5,615	)		(4,706	)
Peru		(11,267	)		(11,880	)
		(302,092	)		(354,916	)
Net deferred tax liability balance	$	(266,103	)	$	(275,433	)

Disclosure of changes in deferred tax assets and liabilities [Table Text Block]

		Year ended			Year ended
		Dec. 31, 2017			Dec. 31, 2016
Net deferred tax liability balance, beginning of year	$	(275,433	)	$	(253,859	)
Deferred income tax expense		15,032			(21,028	)
Deferred mining tax expense		82			(2,490	)
OCI transactions		(3,845	)		2,198
Items charged directly to equity		2,238			-
Foreign currency translation on the deferred tax liability		(4,177	)		(254	)
Net deferred tax liability balance, end of year	$	(266,103	)	$	(275,433	)

Disclosure of reconciliation to statutory tax rate [Table Text Block]

		Year ended
		December 31,
		2017			2016
Statutory tax rate		27.00%			27.00%
Tax expense at statutory rate	$	53,656		$	1,513
Effect of:
Deductions related to mining taxes		(6,075	)		(3,223	)
Adjusted income taxes		47,581			(1,710	)
Mining tax expense		19,367			12,771
		66,948			11,061
Permanent differences related to:
Capital items		1,462			401
Other income tax permanent differences		338			262
Impact of remeasurement on decommissioning liability		15,290			13,803
Temporary income tax differences not recognized		10,015			8,598
Impact related to differences in tax rates in foreign operations		4,605			2,250
Impact of changes to statutory tax rate		(52,855	)		7,960
Foreign exchange on non-monetary items		(9,387	)		(3,433	)
Impact related to tax assessments and tax return amendments		(1,587	)		(104	)
Tax expense	$	34,829		$	40,798

Disclosure of temporary differences recognized [Table Text Block]

		Balance sheet						Income Statement
								Year ended			Year ended
		Dec. 31,			Dec. 31,			Dec. 31,			Dec. 31,
		2017			2016			2017			2016
Deferred income tax (liability) asset/
expense (recovery)
Property, plant and equipment	$	(102,053	)	$	1,163		$	103,216		$	(255	)
Pension obligation		10,034			942			(12,937	)		(215	)
Other employee benefits		16,742			2,972			(13,770	)		(1,471	)
Non-capital losses		91,495			59,034			(32,461	)		(24,098	)
Share issue and debt costs		15,707			16,319			2,850			(14,858	)
Other		4,064			(947	)		(8,810	)		2,084
Deferred income tax asset / expense (recovery)		35,989			79,483			38,088			(38,813	)
Deferred income tax liability (asset)/ (recovery) expense
Property, plant and equipment		313,581			417,060			(103,479	)		22,810
Pension obligation		-			(12,150	)		12,150			4,556
Other employee benefits		192			(14,806	)		14,998			(2,111	)
Asset retirement obligations		(789	)		(11,357	)		10,568			4,701
Non-capital losses		(27,539	)		(46,500	)		18,961			21,567
Other		(235	)		6,083			(6,318	)		8,318
Deferred income tax liability/ (recovery) expense		285,210			338,330			(53,120	)		59,841
Deferred income tax liability/
(recovery) expense	$	(249,221	)	$	(258,847	)	$	(15,032	)	$	21,028

Disclosure of temporary differences not recognized [Table Text Block]

		Dec. 31,		Dec. 31,
		2017		2016
Property, plant and equipment	$	32,089	$	16,690
Capital losses		223,916		109,670
Other employee benefits		78,871		52,093
Asset retirement obligations		174,448		135,481
Non-capital losses		104,171		99,737
Temporary differences not recognized	$	613,495	$	413,671

Disclosure of temporary differences - deferred mining tax assets and liabilities [Table Text Block]

		Dec. 31,			Dec. 31,
Canada		2017			2016
Property, plant and equipment	$	(5,615	)	$	(4,706	)
		Dec. 31,			Dec. 31,
Peru		2017			2016
Property, plant and equipment	$	(11,267	)	$	(11,880	)