Basic and Diluted Earnings per Common Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Jul. 31, 2018	Jul. 31, 2017
Earnings Per Share Disclosure [Line Items]
Net (loss) income attributable to Korn/Ferry International	$ (38,611)	$ 29,041
Less: distributed and undistributed earnings to nonvested restricted stockholders	59	288
Basic net (loss) earnings attributable to common stockholders	(38,670)	28,753
Add: undistributed earnings to nonvested restricted stockholders		232
Less: reallocation of undistributed earnings to nonvested restricted stockholders		230
Diluted net (loss) earnings attributable to common stockholders	$ (38,670)	$ 28,755
Basic weighted-average number of common shares outstanding	55,378	55,795
Diluted weighted-average number of common shares outstanding	55,378	56,403
Basic (loss) earnings per share	$ (0.70)	$ 0.52
Diluted (loss) earnings per share	$ (0.70)	$ 0.51
ESPP
Earnings Per Share Disclosure [Line Items]
Stock		8
Restricted Stock
Earnings Per Share Disclosure [Line Items]
Stock		588
Stock Options
Earnings Per Share Disclosure [Line Items]
Stock		12

Earnings Per Share Disclosure [Line Items]

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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