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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of noncash expense for share-based payment arrangement.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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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).

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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.

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

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Gross number of share options (or share units) granted during the period.

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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 award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Stock-Based Compensation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-Based Compensation [Abstract]
Stock-based compensation cost	$ 2.7	$ 3.2	$ 4.4	$ 5.2
Unrecognized compensation expenses and recognition period [Abstract]
Unrecognized compensation expense	14.0		$ 14.0
Weighted-average remaining service period			2 years 7 months 6 days
Stock Options [Member]
Type and fair value of stock-based compensation awards granted [Abstract]
Options granted (in shares)			0.3	0.2
Fair value of options granted (in dollars per share)			$ 5.56	$ 7.81
Assumptions used in determining fair value of options [Abstract]
Expected life of awards			6 years 3 months 18 days	6 years 3 months 18 days
Risk-free interest rate			2.20%	2.80%
Expected volatility of the Company's stock			39.20%	39.70%
Expected dividend yield on the Company's stock			0.00%	0.00%
Unrecognized compensation expenses and recognition period [Abstract]
Unrecognized compensation expense	3.1		$ 3.1
Weighted-average remaining service period			2 years 10 months 24 days
Restricted Stock Awards [Member]
Type and fair value of stock-based compensation awards granted [Abstract]
Stock granted (in shares)			0.3	0.2
Fair value of stock granted (in dollars per share)			$ 13.26	$ 17.90
Unrecognized compensation expenses and recognition period [Abstract]
Unrecognized compensation expense	7.1		$ 7.1
Weighted-average remaining service period			2 years 9 months 18 days
Performance Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Additional General Disclosures [Abstract]
Award performance period			3 years
Type and fair value of stock-based compensation awards granted [Abstract]
Stock granted (in shares)			0.3	0.2
Fair value of stock granted (in dollars per share)			$ 13.26	$ 17.90
Unrecognized compensation expenses and recognition period [Abstract]
Unrecognized compensation expense	$ 3.8		$ 3.8
Weighted-average remaining service period			2 years 1 month 6 days
Unrestricted Stock Awards [Member]
Type and fair value of stock-based compensation awards granted [Abstract]
Stock granted (in shares)			0.1	0.1
Fair value of stock granted (in dollars per share)			$ 14.50	$ 17.60