Financial Instruments (Contractual Maturities of Types of Securities) (Details) $ in Millions	Oct. 31, 2018 USD ($)
Cost
Due within 1 year	$ 146.8
Due in 1 year through 5 years	111.0
Due in 5 years through 10 years	3.6
Due after 10 years	0.9
Amortized Cost	262.3
Fair Value
Due within 1 year	148.2
Due in 1 year through 5 years	110.3
Due in 5 years through 10 years	3.6
Due after 10 years	0.9
Total	$ 263.0

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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