Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Sep. 30, 2022 USD ($)
Amortized Cost Maturities:
Within one year	$ 448.4
One to five years	1,139.6
Six to ten years	9.0
More than ten years	13.5
Marketable debt securities, Cost	1,610.5
Fair Value Maturities:
Within one year	442.4
One to five years	1,078.6
Six to ten years	8.9
More than ten years	11.8
Fair Value	$ 1,541.7

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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