Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jan. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Impairment Loss	$ 0	$ 0
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2019			$ 109,100,000
2020			136,100,000
2021			134,800,000
2022			132,900,000
2022			130,700,000
Thereafter			861,600,000
Total remaining amortization for intangible assets			$ 1,505,200,000