Business Segments - Financial Highlights by Business Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Segment Reporting Information [Line Items]
Total revenue	$ 486,172	$ 460,770	$ 1,471,327	$ 1,331,155
Net income attributable to Korn Ferry	44,964	27,247	52,387	92,619
Net income attributable to noncontrolling interest	480	180	1,782	969
Other loss (income), net	(2,401)	(7,510)	(2,292)	(14,311)
Interest expense, net	4,282	3,710	12,722	11,014
Equity in earnings of unconsolidated subsidiaries, net	(62)	(97)	(191)	(187)
Income tax (benefit) provision	15,420	26,316	14,143	54,145
Operating income (loss)	62,683	49,846	78,551	144,249
Depreciation and amortization	11,741	12,225	34,490	36,881
Other income (loss), net	2,401	7,510	2,292	14,311
Equity in earnings of unconsolidated subsidiaries	62	97	191	187
EBITDA	76,887	69,678	115,524	195,628
Restructuring (recoveries) charges, net				78
Integration/acquisition costs	804	1,673	6,746	6,654
Tradename write-offs			106,555
Adjusted EBITDA	77,691	71,351	228,825	202,360
Fee Revenue
Segment Reporting Information [Line Items]
Total revenue	474,504	447,581	1,435,277	1,291,853
Operating Segments | Executive Search
Segment Reporting Information [Line Items]
Total revenue	197,983	185,493	598,033	531,883
Operating income (loss)	44,703	34,434	137,048	102,638
Depreciation and amortization	1,807	1,922	5,172	5,651
Other income (loss), net	1,589	847	1,724	1,776
Equity in earnings of unconsolidated subsidiaries	62	97	191	187
EBITDA	48,161	37,300	144,135	110,252
Restructuring (recoveries) charges, net				313
Adjusted EBITDA	48,161	37,300	144,135	110,565
Operating Segments | Executive Search | North America
Segment Reporting Information [Line Items]
Total revenue	117,725	106,332	352,804	305,866
Operating income (loss)	30,596	21,408	92,438	66,517
Depreciation and amortization	970	990	2,917	2,923
Other income (loss), net	1,564	585	955	1,157
Equity in earnings of unconsolidated subsidiaries	62	97	191	187
EBITDA	33,192	23,080	96,501	70,784
Adjusted EBITDA	33,192	23,080	96,501	70,784
Operating Segments | Executive Search | EMEA
Segment Reporting Information [Line Items]
Total revenue	46,639	47,763	140,024	130,894
Operating income (loss)	7,525	7,329	21,813	20,349
Depreciation and amortization	402	458	867	1,345
Other income (loss), net	26	37	388	136
EBITDA	7,953	7,824	23,068	21,830
Adjusted EBITDA	7,953	7,824	23,068	21,830
Operating Segments | Executive Search | Asia Pacific
Segment Reporting Information [Line Items]
Total revenue	26,046	24,942	80,817	73,009
Operating income (loss)	5,929	5,289	19,337	12,811
Depreciation and amortization	338	361	1,083	1,052
Other income (loss), net	(134)	185	118	384
EBITDA	6,133	5,835	20,538	14,247
Restructuring (recoveries) charges, net				313
Adjusted EBITDA	6,133	5,835	20,538	14,560
Operating Segments | Executive Search | Latin America
Segment Reporting Information [Line Items]
Total revenue	7,573	6,456	24,388	22,114
Operating income (loss)	653	408	3,460	2,961
Depreciation and amortization	97	113	305	331
Other income (loss), net	133	40	263	99
EBITDA	883	561	4,028	3,391
Adjusted EBITDA	883	561	4,028	3,391
Operating Segments | Advisory
Segment Reporting Information [Line Items]
Total revenue	205,677	201,961	627,243	589,093
Operating income (loss)	29,279	27,057	(24,374)	72,459
Depreciation and amortization	7,307	7,882	21,702	24,110
Other income (loss), net	786	768	1,621	1,654
EBITDA	37,372	35,707	(1,051)	98,223
Restructuring (recoveries) charges, net				(241)
Integration/acquisition costs	777	1,593	6,559	6,455
Tradename write-offs			106,555
Adjusted EBITDA	38,149	37,300	112,063	104,437
Operating Segments | RPO & Professional Search
Segment Reporting Information [Line Items]
Total revenue	82,512	73,316	246,051	210,179
Operating income (loss)	12,176	10,064	36,337	27,727
Depreciation and amortization	803	733	2,325	2,313
Other income (loss), net	77	2	103	10
EBITDA	13,056	10,799	38,765	30,050
Restructuring (recoveries) charges, net				6
Adjusted EBITDA	13,056	10,799	38,765	30,056
Operating Segments | Fee Revenue | Executive Search
Segment Reporting Information [Line Items]
Total revenue	193,396	180,416	583,954	518,373
Operating Segments | Fee Revenue | Executive Search | North America
Segment Reporting Information [Line Items]
Total revenue	114,215	102,716	342,175	296,093
Operating Segments | Fee Revenue | Executive Search | EMEA
Segment Reporting Information [Line Items]
Total revenue	45,940	46,782	137,522	128,249
Operating Segments | Fee Revenue | Executive Search | Asia Pacific
Segment Reporting Information [Line Items]
Total revenue	25,687	24,493	79,918	71,983
Operating Segments | Fee Revenue | Executive Search | Latin America
Segment Reporting Information [Line Items]
Total revenue	7,554	6,425	24,339	22,048
Operating Segments | Fee Revenue | Advisory
Segment Reporting Information [Line Items]
Total revenue	201,502	198,056	613,966	577,462
Operating Segments | Fee Revenue | RPO & Professional Search
Segment Reporting Information [Line Items]
Total revenue	79,606	69,109	237,357	196,018
Corporate
Segment Reporting Information [Line Items]
Operating income (loss)	(23,475)	(21,709)	(70,460)	(58,575)
Depreciation and amortization	1,824	1,688	5,291	4,807
Other income (loss), net	(51)	5,893	(1,156)	10,871
EBITDA	(21,702)	(14,128)	(66,325)	(42,897)
Integration/acquisition costs	27	80	187	199
Adjusted EBITDA	$ (21,675)	$ (14,048)	$ (66,138)	$ (42,698)