Share Capital - Summary of Status of Share Unit Plan for Other Equity Instruments (Detail) - shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Time Based Share Units [Member]
Disclosure of Compensation Related Costs, Share based Payments [Abstract]
Beginning balance	1,045,250	1,036,500
Issued	1,553,125	452,125
Exercised	(325,875)	(364,000)
Forfeited	(125,000)	(79,375)
Ending balance	2,147,500	1,045,250
Expected to vest	2,147,500	1,045,250
Expected to vest	2,147,500	1,045,250
Weighted average contractual life (years)	3 years 10 days	2 years 8 months 26 days
Performance Based Share Units [Member]
Disclosure of Compensation Related Costs, Share based Payments [Abstract]
Beginning balance	1,500,000	1,350,000
Issued		150,000
Forfeited	(550,000)
Ending balance	950,000	1,500,000
Expected to vest		1,100,000
Expected to vest	950,000	1,500,000
Weighted average contractual life (years)	7 years 7 days	7 years 11 months 26 days

Compensation Related Costs Share Based Payments Disclosure [Line Items]

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised

+ References

No definition available.

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expected To Vest In Period

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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