Summary of Phantom Stock Activity (Detail) - $ / shares	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average Grant-Date Fair Value, Beginning Balance Outstanding	$ 23.58	$ 39.53	$ 48.68
Weighted-average Grant-Date Fair Value, Granted		6.83	19.14
Weighted-average Grant-Date Fair Value, Ending Balance Outstanding	$ 24.19	$ 23.58	$ 39.53
Number of Shares Beginning Balance Outstanding	363,630	185,060	146,388
Number of Shares, Granted		168,380	56,370
Number of Shares Ending Balance Outstanding	350,838	363,630	185,060
Phantom Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average Grant-Date Fair Value, Beginning Balance Outstanding	$ 10.83	$ 24.07	$ 50.94
Weighted-average Grant-Date Fair Value, Granted		7.21	22.80
Weighted-average Grant-Date Fair Value, Vested	12.29	24.92	48.47
Weighted-average Grant-Date Fair Value, Cancelled/forfeited	13.52	23.93	50.70
Weighted-average Grant-Date Fair Value, Ending Balance Outstanding	$ 9.74	$ 10.83	$ 24.07
Phantom Stock Plan \| Time Based Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Beginning Balance Outstanding	1,598,538	567,471	60,882
Number of Shares, Granted		1,246,972	546,058
Number of Shares, Vested	(584,136)	(190,052)	(33,987)
Number of Shares, Cancelled/forfeited	(68,252)	(25,853)	(5,482)
Number of Shares Ending Balance Outstanding	946,150	1,598,538	567,471
Phantom Stock Plan \| Performance Based Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Beginning Balance Outstanding	1,291	1,291	1,291
Number of Shares, Vested	(1,290)
Number of Shares, Cancelled/forfeited	(1)
Number of Shares Ending Balance Outstanding		1,291	1,291

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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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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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)
-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
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-SubTopic 10
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-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
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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
-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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