Non-Vested Stock Option Activity (Detail) (Stock Option [Member], USD $)	12 Months Ended
Dec. 31, 2014
Stock Option [Member]
Share Based Compensation [Line Items]
Non-vested stock options beginning balance	0
Granted	250,000
Vested	0
Forfeited	0
Non-vested stock options ending balance	250,000
Non-Vested Stock Options Begining Balance, Weighted Average Grant Date Fair Value	$ 0
Non-Vested Stock Options Granted, Weighted Average Grant Date Fair Value	$ 26.65
Non-Vested Stock Options Vested, Weighted Average Grant Date Fair Value	$ 0
Non-Vested Stock Options Forfeited, Weighted Average Grant Date Fair Value	$ 0
Non-Vested Stock Options Ending Balance, Weighted Average Grant Date Fair Value	$ 26.65

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Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ 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 (d)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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- Definition

Number of non-vested options outstanding.

+ References

No definition available.

+ Details

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- Definition

Number of non-vested options forfeited.

+ References

No definition available.

+ Details

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- Definition

Weighted average grant-date fair value of non-vested options forfeited.

+ References

No definition available.

+ Details

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- Definition

Weighted average grant-date fair value of non-vested options outstanding.

+ References

No definition available.

+ Details

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- Definition

Number of options vested.

+ References

No definition available.

+ Details

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- Definition

Weighted average grant-date fair value of options vested.

+ References

No definition available.

+ Details

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