Basic and Diluted (Loss) Earnings Per Share - Basic and Diluted (Loss) Earnings per Common Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Earnings Per Share Disclosure [Line Items]
Net (loss) income attributable to Korn Ferry	$ (30,833)	$ 42,951
Less: distributed and undistributed earnings to nonvested restricted stockholders	144	444
Basic net (loss) earnings attributable to common stockholders	(30,977)	42,507
Add: undistributed earnings to nonvested restricted stockholders		386
Less: reallocation of undistributed earnings to nonvested restricted stockholders		384
Diluted net (loss) earnings attributable to common stockholders	$ (30,977)	$ 42,509
Basic weighted-average number of common shares outstanding	53,264	55,266
Diluted weighted-average number of common shares outstanding	53,264	55,635
Basic (loss) earnings per share	$ (0.58)	$ 0.77
Diluted (loss) earnings per share	$ (0.58)	$ 0.76
ESPP
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities		12
Restricted Stock
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities		357