Basic and Diluted Earnings Per Share - Basic and Diluted Earnings per Common Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Earnings Per Share Disclosure [Line Items]
Net income attributable to Korn Ferry	$ 51,319	$ 19,993	$ 48,264	$ 105,748
Less: distributed and undistributed earnings to nonvested restricted stockholders	1,377	222	1,149	1,138
Basic net earnings attributable to common stockholders	49,942	19,771	47,115	104,610
Add: undistributed earnings to nonvested restricted stockholders	1,232	161	714	960
Less: reallocation of undistributed earnings to nonvested restricted stockholders	1,222	160	709	953
Diluted net earnings attributable to common stockholders	$ 49,952	$ 19,772	$ 47,120	$ 104,617
Basic weighted-average number of common shares outstanding	52,596	53,999	53,030	54,611
Diluted weighted-average number of common shares outstanding	53,013	54,264	53,396	55,006
Basic earnings per share	$ 0.95	$ 0.37	$ 0.89	$ 1.92
Diluted earnings per share	$ 0.94	$ 0.36	$ 0.88	$ 1.90
Restricted Stock
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities	414	258	352	363
ESPP
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities	3	7	14	32