Summary of Acquisition (Parenthetical) (Detail) - USD ($)			3 Months Ended									12 Months Ended
		Dec. 01, 2015	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016		Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2017	Apr. 30, 2016		Apr. 30, 2015		Nov. 23, 2015	Mar. 01, 2015
Business Acquisition [Line Items]
Common stock, par value			$ 0.01				$ 0.01					$ 0.01	$ 0.01
Fee revenue			$ 406,065,000	$ 381,918,000	$ 401,917,000	$ 375,621,000	$ 399,960,000		$ 344,158,000	$ 280,600,000	$ 267,394,000	$ 1,565,521,000	$ 1,292,112,000		$ 1,028,152,000
Assets	[1]		2,062,898,000				1,898,600,000					2,062,898,000	1,898,600,000		1,317,801,000
Adjusted EBITDA												234,976,000	190,229,000		161,691,000
Acquisition of a business, purchase price			0				476,885,000	[2]				0	476,885,000	[2]	17,496,000	[3]
Legacy Hay
Business Acquisition [Line Items]
Business combination, aggregate purchase price		$ 476,900,000
Payment to acquire business		$ 259,000,000
Business combination, Consideration Shares		5,922,136
Business combination, Consideration Shares value		$ 217,900,000
Common stock, par value		$ 0.01
Business combination, committed to retention pool for certain employees		$ 40,000,000
Business combination, committed to retention pool for certain employees, paid												9,000,000
Business combination, committed to retention pool for certain employees, percentage payable within 45 days after November 30, 2017		50.00%
Business combination, committed to retention pool for certain employees, percentage payable within 45 days after November 30, 2018		50.00%
Fee revenue													186,800,000
Assets							740,200,000						740,200,000
Adjusted EBITDA													$ 28,500,000
Adjusted EBITDA margin													14.40%
Pivot Leadership
Business Acquisition [Line Items]
Fee revenue															3,700,000
Assets															$ 20,000,000
Acquisition of a business, purchase price																		$ 17,500,000
Acquisition of a business, contingent consideration			6,500,000									6,500,000						$ 2,200,000
Tax deductible goodwill			7,400,000				7,400,000					7,400,000	$ 7,400,000
Acquisition of a business, contingent consideration paid												$ 1,100,000
Pivot Leadership | Minimum
Business Acquisition [Line Items]
Business acquisition contingent consideration payable, through year												2017
Pivot Leadership | Maximum
Business Acquisition [Line Items]
Business acquisition contingent consideration payable, through year												2020
Foreign Locations | Legacy Hay
Business Acquisition [Line Items]
Payment to acquire business		$ 54,000,000
Other Liabilities | Pivot Leadership
Business Acquisition [Line Items]
Acquisition of a business, contingent consideration fair value			$ 1,300,000				$ 3,000,000					$ 1,300,000	$ 3,000,000
Term Facility
Business Acquisition [Line Items]
Senior unsecured loan, aggregate principal amount																	$ 150,000,000

[1] As of the end of the fiscal year.

[2] On December 1, 2015, the Company completed its acquisition of Legacy Hay, a global leader in people strategy and organizational performance, for $476.9 million, net of cash acquired. The purchase price consisted of $259.0 million in cash ($54 million from foreign locations), net of estimated cash acquired and 5,922,136 shares of the Company's common stock, par value $0.01 per share (the "Consideration Shares"), representing an aggregate value of $217.9 million based on the closing price of the Company's common stock on The New York Stock Exchange on November 30, 2015. On November 23, 2015, the Company borrowed $150 million from the Term Facility, to finance a portion of the Legacy Hay acquisition purchase price. As part of the acquisition, the Company has committed to a $40 million retention pool (of which $9.0 million was paid in fiscal 2017) for certain employees of Legacy Hay subject to certain circumstances. Of the remaining balance, 50% will be payable within 45 days after November 30, 2017 and the remaining 50% will be payable within 45 days after November 30, 2018. The acquisition strengthens the Company's intellectual property, enhances our geographical presence, adds complimentary capabilities to further leverage search relationships and broadens capabilities for assessment and development. It improves our ability to support the global business community not only in attracting top talent and designing compensation and reward incentives, but also with an integrated approach to the entire leadership and people continuum. Actual results of operations of Legacy Hay are included in the Company's consolidated financial statements from December 1, 2015, the effective date of the acquisition, and includes $186.8 million, $740.2 million and $28.5 million in fee revenue, total assets and Adjusted EBITDA, respectively, with an Adjusted EBITDA margin of 14.4%, during fiscal 2016. Legacy Hay is included in the Hay Group segment.

[3] On March 1, 2015, the Company acquired all outstanding membership interests of Pivot Leadership, a global provider of innovative, customized and scalable executive development programs, for $17.5 million, net of cash acquired, which includes $2.2 million in contingent consideration. As of April 30, 2017 and 2016, the fair value of the contingent consideration is $1.3 million and $3.0 million and is included in other liabilities in the accompanying consolidated balance sheets. The contingent consideration is based on the achievement of certain revenue targets and can be up to $6.5 million, payable in four installments in fiscal 2017 to 2020. In fiscal 2017, the Company paid $1.1 million due to meeting certain revenue targets. The acquisition allows us to integrate the Company's talent management solution with Pivot's executive learning capabilities. Actual results of operations of Pivot Leadership are included in the Company's consolidated financial statements from March 1, 2015, the effective date of the acquisition, and includes $3.7 million and $20.0 million in fee revenue and total assets, respectively, during fiscal 2015. Tax deductible goodwill from the Pivot Leadership acquisition was $7.4 million as of April 30, 2017 and 2016.