Fee Revenue - Schedule of Disaggregation of Fee Revenue by Industry (Detail) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Apr. 30, 2019 |
Jan. 31, 2019 |
Oct. 31, 2018 |
Jul. 31, 2018 |
Apr. 30, 2018 |
Jan. 31, 2018 |
Oct. 31, 2017 |
Jul. 31, 2017 |
Apr. 30, 2019 |
Apr. 30, 2018 |
Apr. 30, 2017 |
|
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 1,973,862 | $ 1,819,519 | $ 1,621,669 | ||||||||
| Industrial | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 561,029 | $ 530,547 | $ 459,732 | ||||||||
| Fee Revenue, Percentage | 29.10% | 30.00% | 29.40% | ||||||||
| Financial Services | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 349,968 | $ 305,047 | $ 257,671 | ||||||||
| Fee Revenue, Percentage | 18.20% | 17.30% | 16.40% | ||||||||
| Life Sciences/ Healthcare | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 323,091 | $ 294,999 | $ 273,493 | ||||||||
| Fee Revenue, Percentage | 16.80% | 16.70% | 17.50% | ||||||||
| Consumer Goods | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 297,676 | $ 276,979 | $ 263,671 | ||||||||
| Fee Revenue, Percentage | 15.50% | 15.70% | 16.80% | ||||||||
| Technology | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 260,918 | $ 226,142 | $ 198,867 | ||||||||
| Fee Revenue, Percentage | 13.50% | 12.80% | 12.70% | ||||||||
| Education/Non-Profit | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 122,524 | $ 120,809 | $ 99,978 | ||||||||
| Fee Revenue, Percentage | 6.30% | 6.80% | 6.40% | ||||||||
| General | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 10,827 | $ 12,694 | $ 12,109 | ||||||||
| Fee Revenue, Percentage | 0.60% | 0.70% | 0.80% | ||||||||
| Fee Revenue | |||||||||||
| Disaggregation Of Revenue [Line Items] | |||||||||||
| Fee Revenue | $ 490,756 | $ 474,504 | $ 495,205 | $ 465,568 | $ 475,364 | $ 447,581 | $ 443,018 | $ 401,254 | $ 1,926,033 | $ 1,767,217 | $ 1,565,521 |
| Fee Revenue, Percentage | 100.00% | 100.00% | 100.00% | ||||||||