Summary of Restricted Stock Activity (Detail) (USD $)	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average Grant-Date Fair Value, Beginning Balance Outstanding	$ 48.68	$ 50.48	$ 50.56
Weighted-average Grant-Date Fair Value, Granted	$ 19.14	$ 49.47	$ 50.48
Weighted-average Grant-Date Fair Value, Ending Balance Outstanding	$ 39.53	$ 48.68	$ 50.48
Number of Shares Beginning Balance Outstanding	146,388	144,007	114,580
Number of Shares, Granted	56,370	26,550	26,955
Number of Shares Ending Balance Outstanding	185,060	146,388	144,007
Restricted Stock Units (RSUs) \| Time Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average Grant-Date Fair Value, Beginning Balance Outstanding	$ 50.24	$ 51.69	$ 54.18
Weighted-average Grant-Date Fair Value, Granted	$ 54.48	$ 49.37	$ 50.16
Weighted-average Grant-Date Fair Value, Vested	$ 50.92	$ 52.22	$ 54.17
Weighted-average Grant-Date Fair Value, Cancelled/forfeited	$ 49.62	$ 52.43	$ 54.18
Weighted-average Grant-Date Fair Value, Ending Balance Outstanding	$ 49.50	$ 50.24	$ 51.69
Number of Shares Beginning Balance Outstanding	495,209	417,665	248,288
Number of Shares, Granted	551	265,937	259,158
Number of Shares, Vested	(237,229)	(175,673)	(79,507)
Number of Shares, Cancelled/forfeited	(7,381)	(12,720)	(10,274)
Number of Shares Ending Balance Outstanding	251,150	495,209	417,665
Restricted Stock Units (RSUs) \| Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average Grant-Date Fair Value, Beginning Balance Outstanding		$ 69.62	$ 72.23
Weighted-average Grant-Date Fair Value, Granted		$ 56.44	$ 67.11
Weighted-average Grant-Date Fair Value, Cancelled/forfeited			$ 72.23
Weighted-average Grant-Date Fair Value, Ending Balance Outstanding	$ 53.58	$ 53.58	$ 69.62
Number of Shares Beginning Balance Outstanding		165,241	84,394
Number of Shares, Granted		91,132	84,323
Number of Shares, Cancelled/forfeited			(3,476)
Number of Shares Ending Balance Outstanding	256,373	256,373	165,241

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

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)(1)(iv)(3)

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

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ 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)(3)

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

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 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)

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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

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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-Subparagraph (c)(2)(iii)(2)

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