Note K - Stock-Based Compensation Plans (Details) - Stock Option Activity (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Note K - Stock-Based Compensation Plans (Details) - Stock Option Activity [Line Items]
Number of Shares (in Shares)	981,750	1,117,000	1,122,500	1,118,250
Exercise Price	$ 24.05	$ 21.75	$ 21.28	$ 20.46
Proceeds on Exercise (in Dollars)	$ 23,608	$ 24,294	$ 23,892	$ 22,881
Number of Shares, Granted (in Shares)	89,000	25,000	40,000
Exercise Price, Granted	$ 44.91	$ 44.90	$ 45.02
Proceeds on Exercise, Granted (in Dollars)	3,997	1,122	1,801
Number of Shares, Exercised (in Shares)	(212,250)	(30,500)	(35,750)
Exercise Price, Exercised	$ 19.52	$ 23.58	$ 22.13
Proceeds on Exercise, Exercised (in Dollars)	(4,143)	(720)	(790)
Cancelled (in Shares)	(12,000)
Cancelled	$ 45.08
Cancelled (in Dollars)	$ (540)crmt_ProceedsOnSharesCancelled
Minimum [Member]
Note K - Stock-Based Compensation Plans (Details) - Stock Option Activity [Line Items]
Exercise Price	$ 11.90	$ 11.90	$ 11.90	$ 11.83
Exercise Price, Granted	$ 36.54	$ 44.52	$ 44.14
Exercise Price, Exercised	$ 11.90	$ 23.34	$ 11.83
Cancelled	$ 41.86
Maximum [Member]
Note K - Stock-Based Compensation Plans (Details) - Stock Option Activity [Line Items]
Exercise Price	$ 50.25	$ 46.44	$ 45.72	$ 45.72
Exercise Price, Granted	$ 50.25	$ 46.44	$ 45.46
Exercise Price, Exercised	$ 45.46	$ 23.75	$ 23.34
Cancelled	$ 45.72

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The cash inflow associated with the amount received from holders on the exercise of granted stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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The cash inflow associated with the amount received from holders on the exercise of outstanding stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Represents the proceeds from cancellation of the shares.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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