Organization and Summary of Significant Accounting Policies - Additional Information (Detail)			12 Months Ended
	Mar. 31, 2020 USD ($)	Nov. 01, 2019 USD ($) Facility	Apr. 30, 2020 USD ($) Segment Facility	Apr. 30, 2019 USD ($)	Apr. 30, 2018 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of business segments | Segment			4
Dividends received from unconsolidated subsidiary			$ 346,000	$ 140,000	$ 240,000
Other-than-temporary impairment			0	0	0
ROU assets, impairment charge			2,282,000
Write-off of long-lived assets			2,654,000
Impairment of long-lived assets				0	0
Goodwill			613,943,000	578,298,000	584,222,000
Impairment of goodwill	$ 0
Impairment of intangible assets			0
Purchase price allocated to indefinite lived trade name intangible assets				106,600,000
Performance-related bonus expenses			$ 197,100,000	257,300,000	220,400,000
Percentage that Actuarial gain or loss must exceed the greater of PBO or Market Value Plan Assets			10.00%
Cash surrender value of company owned life insurance policies, net of loans			$ 146,408,000	126,000,000
Accounting Standards Update 2016-02
Organization And Summary Of Significant Accounting Policies [Line Items]
ROU assets			236,100,000
Lease liability			272,300,000
ROU asset adjusted by reclassification of pre-existing prepaid expenses and other assets			5,100,000
ROU asset adjusted by reclassification of deferred rent			41,300,000
CSV of COLI Contracts
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash surrender value of company owned life insurance policies, net of loans			146,400,000	126,000,000.0
General and Administrative Expenses
Organization And Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets				106,600,000
Foreign currency gains (losses)			(4,100,000)	(1,700,000)	(3,300,000)
Consulting | Operating Segments
Organization And Summary Of Significant Accounting Policies [Line Items]
Goodwill			$ 173,014,000	$ 173,147,000	$ 173,453,000
Acquired Companies
Organization And Summary Of Significant Accounting Policies [Line Items]
Number of office leases closed | Facility		16	16
ROU assets, impairment charge		$ 2,300,000	$ 2,300,000
Goodwill		$ 38,926,000
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Intangible assets estimated useful lives			1 year
Amortization of long-term retention awards			4 years
Minimum | Executive Capital Accumulation Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Deferred compensation arrangement vesting period			4 years
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Intangible assets estimated useful lives			24 years
Amortization of long-term retention awards			5 years
Maximum | Executive Capital Accumulation Plan
Organization And Summary Of Significant Accounting Policies [Line Items]
Deferred compensation arrangement vesting period			5 years
Software and Software Development Costs | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life			3 years
Software and Software Development Costs | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life			7 years
Other Capitalized Property Plant and Equipment | Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life			3 years
Other Capitalized Property Plant and Equipment | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life			10 years
Leasehold Improvements And Furniture And Fixtures | Acquired Companies
Organization And Summary Of Significant Accounting Policies [Line Items]
Write-off of long-lived assets			$ 400,000
Mexican Subsidiary
Organization And Summary Of Significant Accounting Policies [Line Items]
Percentage of Noncontrolling interest in subsidiary			51.00%
Affiliated Entity
Organization And Summary Of Significant Accounting Policies [Line Items]
Investments in affiliated companies maximum			50.00%