Borrowing Arrangements - Fair Value Notes (Details) - Senior Notes - USD ($)	Oct. 31, 2020	Jan. 31, 2020	Dec. 15, 2017	Jun. 30, 2017	Jun. 30, 2015	Dec. 31, 2012
2012 Senior Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	$ 350,000,000.0					$ 350,000,000.0
Fair value	369,100,000
Senior Notes due 2025
Debt Instrument [Line Items]
Aggregate Principal Amount	300,000,000.0				$ 300,000,000
Fair value	340,500,000
2017 Senior Notes
Debt Instrument [Line Items]
Aggregate Principal Amount	500,000,000.0		$ 400,000,000.0	$ 500,000,000.0
Fair value	562,200,000
2.85 Notes due January 15 2030
Debt Instrument [Line Items]
Aggregate Principal Amount	500,000,000.0	$ 500,000,000.0
Fair value	$ 550,400,000