Basic and Diluted Earnings (Loss) Per Share - Basic and Diluted Earnings (Loss) per Common Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Earnings Per Share Disclosure [Line Items]
Net income (loss) attributable to Korn Ferry	$ 27,778	$ 42,804	$ (3,055)	$ 85,755
Less: distributed and undistributed earnings to nonvested restricted stockholders	730	466	289	910
Basic net earnings (loss) attributable to common stockholders	27,048	42,338	(3,344)	84,845
Add: undistributed earnings to nonvested restricted stockholders	585	406		792
Less: reallocation of undistributed earnings to nonvested restricted stockholders	583	405		788
Diluted net earnings (loss) attributable to common stockholders	$ 27,050	$ 42,339	$ (3,344)	$ 84,849
Basic weighted-average number of common shares outstanding	53,229	54,568	53,246	54,917
Diluted weighted-average number of common shares outstanding	53,390	54,716	53,246	55,170
Basic earnings (loss) per share	$ 0.51	$ 0.78	$ (0.06)	$ 1.54
Diluted earnings (loss) per share	$ 0.51	$ 0.77	$ (0.06)	$ 1.54
ESPP
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities	7	10		25
Restricted Stock
Earnings Per Share Disclosure [Line Items]
Effect of dilutive securities	154	138		228