Employee Benefit Plans - Stock options granted (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Weighted average assumptions used in estimating the grant date fair value of stock options granted
Expected life-years	6 years 9 months 18 days	5 years 10 months 24 days	6 years 6 months
Risk-free interest rate (as a percent)	2.20%	2.70%	2.70%
Expected volatility of common stock (as a percent)	47.00%	43.00%	43.00%
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Fair value and intrinsic value information
Weighted average grant date fair value per share of options granted (in dollars per share)	$ 2.52	$ 1.89	$ 2.59
Intrinsic value of options exercised (in dollars)	$ 378	$ 114	$ 2,469

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.

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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.

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- Definition

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

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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.

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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.

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