Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Decrease in operating income	$ (85.1)	$ (80.1)	$ (183.8)	$ (169.2)
Increase in other income, net	0.7	$ 1.4	2.6	$ 2.2
Accounting Standards Update 2017-07
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Decrease in operating income	1.5		3.1
Increase in other income, net	$ 1.5		$ 3.1