Stock-Based Compensation - Assumptions to Estimate Fair Value of Option Grants (Detail)	6 Months Ended
Sep. 30, 2014
2015 $4.61 Value Per Option \| Black Scholes Based Option Pricing Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	30.00%
Risk-free interest rate	2.10%
Expected term of options (in years)	7 years
Forfeiture adjustment	0.00%
2015 $3.85 Value Per Option \| Black Scholes Based Option Pricing Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	30.90%
Risk-free interest rate	2.20%
Expected term of options (in years)	7 years
Forfeiture adjustment	0.00%
2014 $3.03 Value Per Option \| Black Scholes Based Option Pricing Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	31.20%
Risk-free interest rate	1.30%
Expected term of options (in years)	7 years
Forfeiture adjustment	0.00%
2014 $3.01 Value Per Option \| Black Scholes Based Option Pricing Model
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	31.20%
Risk-free interest rate	1.30%
Expected term of options (in years)	7 years
Forfeiture adjustment	0.00%
2015 $3.05 Value Per Option \| Monte Carlo Simulation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	32.30%
Risk-free interest rate	2.60%
Expected term of options (in years)	10 years
Forfeiture adjustment	1.40%
Suboptimal behavior factor	1.6
2015 $2.14 Value Per Option \| Monte Carlo Simulation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	33.70%
Risk-free interest rate	2.50%
Expected term of options (in years)	10 years
Forfeiture adjustment	1.20%
Suboptimal behavior factor	1.6
2014 $1.90 Value Per Option \| Monte Carlo Simulation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	34.90%
Risk-free interest rate	1.90%
Expected term of options (in years)	10 years
Forfeiture adjustment	1.10%
Suboptimal behavior factor	1.7
2014 $1.71 Value Per Option \| Monte Carlo Simulation
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%
Volatility	34.90%
Risk-free interest rate	1.90%
Expected term of options (in years)	10 years
Forfeiture adjustment	1.80%
Suboptimal behavior factor	1.7

Share based compensation arrangement by share based payment award fair value assumptions expected forfeiture rate.

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- Definition

Share based compensation arrangement by share based payment award fair value assumptions suboptimal behavior factor.

+ References

No definition available.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ 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 (f)(2)(iii)

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

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 14.D.2)

-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (f)(2)(i)

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

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

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section D

-Subsection 2

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ 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 (f)(2)(ii)

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

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ 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 (f)(2)(iv)

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

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