Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net cash provided by (used in) operating activities	$ 63.9	$ 101.5
Net cash provided by (used in) financing activities	$ (1.9)	(57.0)
Accounting Standards Update 2016-09
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net cash provided by (used in) operating activities		1.8
Net cash provided by (used in) financing activities		$ 1.8