XML 145 R98.htm IDEA: XBRL DOCUMENT v3.8.0.1
Income Tax Expense and Deferred Taxes - Summary of Temporary Difference (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets $ 58,144 $ 50,295
Deferred tax liabilities 607,270 493,796
Expense (recovery) on the income statement (19,849) 9,039
Property, plant and equipment [member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax liabilities 592,062 482,530
Expense (recovery) on the income statement (33,466) 11,200
Loss carryforwards [member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 31,457 15,436
Expense (recovery) on the income statement (4,641) (1,603)
Liabilities [member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 24,690 20,864
Expense (recovery) on the income statement (80) (3,496)
Investment tax credits [member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Expense (recovery) on the income statement   5,665
Other items [member]    
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]    
Deferred tax assets 1,997 13,995
Deferred tax liabilities 15,208 11,266
Expense (recovery) on the income statement $ 18,338 $ (2,727)