Stock-Based Compensation - Additional Information (Detail) (USD $)	9 Months Ended
Feb. 28, 2013
Non-Qualified Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-qualified stock option, granted	1,012,250
Non-qualified stock option, per share price	$ 20.63
Non-qualified stock option, fair value, per share price	$ 7.71
Pre-tax stock-based compensation	$ 7,014,000
Non-Qualified Stock Options \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	6,450,000
Pre-tax stock-based compensation, period of recognition	3 years
Non-Qualified Stock Options \| Non Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation	564,000
Pre-tax stock-based compensation, period of recognition	1 year
Restricted Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common shares, granted	121,400
Restricted common shares, fair value per share	$ 20.77
Pre-tax stock-based compensation	2,299,000
Restricted Common Shares \| Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation, period of recognition	3 years
Pre-tax stock-based compensation	1,796,000
Restricted Common Shares \| Non Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax stock-based compensation, period of recognition	1 year
Pre-tax stock-based compensation	$ 503,000

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Aggregate unrecognized cost of share-based awards, other than options, made to employees under an equity-based compensation plan, that have yet to vest.

+ References

No definition available.

+ Details

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- Definition

Aggregate unrecognized cost of option awards made to employees under a stock option plan or plans, that have yet to vest.

+ References

No definition available.

+ Details

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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

+ Details

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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

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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- Definition

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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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

Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

+ References

No definition available.

+ Details

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