Capital Stock - Summary of Company's Restricted Share Award Activity (Detail) (Restricted share award [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted share award [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Stock Awards Outstanding, Beginning balance	1,842,351	1,156,078
Number of Restricted Stock Awards Outstanding, Restricted stock awards granted	500,894	686,273	1,156,078
Number of Restricted Stock Awards Outstanding, Ending balance	2,343,245	1,842,351	1,156,078
Weighted Average Grant Date Fair Value, Beginning balance	$ 0.6787	$ 0.4761
Weighted Average Grant Date Fair Value, Restricted stock awards granted	$ 2.6602	$ 1.0200	$ 0.4761
Weighted Average Grant Date Fair Value, Ending balance	$ 1.1023	$ 0.6787	$ 0.4761
Aggregate Intrinsic Value, Beginning balance	$ 1,250	$ 550
Aggregate Intrinsic Value, Restricted stock awards granted	1,332	700	550
Aggregate Intrinsic Value, Ending balance	$ 2,582	$ 1,250	$ 550

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).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-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=6415400&loc=d3e5070-113901

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- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued 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

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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://www.xbrl.org/2003/role/presentationRef

-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=6415400&loc=d3e5070-113901

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-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=6415400&loc=d3e5070-113901

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options grants in period aggregate intrinsic value.

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options outstanding aggregate intrinsic value.

+ References

No definition available.

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