Intangible Assets (Intangible Assets with Finite Lives) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Jan. 31, 2021	Jul. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 449,933,000			$ 449,933,000
Accumulated Amortization	186,583,000			181,234,000
Net Carrying Amount	263,350,000			268,699,000
Amortization of intangibles	$ 5,349,000	$ 5,566,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	20 years 2 months 12 days		20 years 2 months 12 days
Gross Carrying Amount	$ 302,058,000			302,058,000
Accumulated Amortization	96,786,000			93,215,000
Net Carrying Amount	$ 205,272,000			208,843,000
Technologies
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	14 years 9 months 18 days		14 years 9 months 18 days
Gross Carrying Amount	$ 114,949,000			114,949,000
Accumulated Amortization	72,143,000			70,924,000
Net Carrying Amount	$ 42,806,000			44,025,000
Trademarks and other
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	16 years 8 months 12 days		16 years 8 months 12 days
Gross Carrying Amount	$ 32,926,000			32,926,000
Accumulated Amortization	17,654,000			17,095,000
Net Carrying Amount	$ 15,272,000			$ 15,831,000