Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Immediately vested common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	34,480	33,487
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	276,000
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures	$ 3.5
Weighted-average period over which unrecognized compensation expense is expected to be recognized	2 years 1 month
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		16,667
Vesting period	8 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures	$ 0.2
Weighted-average period over which unrecognized compensation expense is expected to be recognized	8 months
Options granted in period (in shares)	0	0
Minimum \| Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years	2 years
Maximum \| Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	3 years

Unrecognized cost of unvested share-based compensation awards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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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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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=109197908&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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