Acquisition - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended				9 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended
	Jan. 31, 2013 Country	Jan. 31, 2012	Jan. 31, 2013 Country	Jan. 31, 2012	Jan. 31, 2013 PDI Ninth House Installment	Dec. 31, 2012 PDI Ninth House	Jan. 31, 2013 Minimum PDI Ninth House Country	Sep. 30, 2012 Global Novations, LLC	Jan. 31, 2013 Global Novations, LLC	Jan. 31, 2013 Global Novations, LLC	Sep. 30, 2012 Global Novations, LLC Minimum Country
Business Acquisition [Line Items]
Acquisition of a business, purchase price	$ 126,917,000		$ 126,917,000		$ 92,446,000	$ 92,500,000
Acquisition of a business, contingent consideration						14,900,000
Acquisition of a business, contingent consideration number of installment payments					3
Acquisition of a business, cost savings due to synergies					8,000,000
Number of years in business							45 years	30 years
Number of countries in which entity operates	35		35				20
Acquisition of a business, net of the cash			112,064,000					34,500,000
Offerings designed to develop leaders								150
Number of countries in which the entity has provided services											40
Fee revenue	$ 202,004,000	$ 185,951,000	$ 584,929,000	$ 592,418,000					$ 11,600,000	$ 16,800,000