Borrowing Arrangements - Fair Value Notes (Details) - Senior Notes - USD ($) $ in Millions	Jul. 31, 2021	Jan. 31, 2020	Jun. 30, 2015	Dec. 31, 2012
2012 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 350.0			$ 350.0
Fair value	362.4
2015 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	300.0		$ 300.0
Fair value	336.4
2017 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	500.0
Fair value	557.1
2020 Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	500.0	$ 500.0
Fair value	$ 534.7