Stockholders' Equity - Exchangeable Shares, Share Repurchase Program and Secondary Public Offering (Details) $ / shares in Units, $ in Millions				12 Months Ended
	Sep. 09, 2019 $ / shares shares	Jun. 13, 2019 shares	Jun. 01, 2018 shares	Apr. 30, 2021 USD ($) shares	Apr. 30, 2020 shares	Apr. 30, 2019 USD ($) shares
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased (shares)				134,000	0	1,000,000.0
Shares repurchased, cost | $				$ 4.2		$ 16.5
Remaining amount under repurchase program | $				54.3
AEA Investors LP | Selling Stockholders
Equity, Class of Treasury Stock [Line Items]
Shares sold (in shares)	6,800,000
Price to the public (in dollars per share) | $ / shares	$ 27.20
Maximum
Equity, Class of Treasury Stock [Line Items]
Authorized amount of shares to be repurchased under the program | $				$ 75.0
Titan
Equity, Class of Treasury Stock [Line Items]
Issuance of shares to current shareholders of Titan (in shares)			1,100,000
Exchangeable shares conversion ratio			1
Duration which stock can not be transferred			1 year
Exchangeable shares converted (in shares)		1,100,000