Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Jun. 30, 2022 USD ($)
Amortized Cost Maturities:
Within one year	$ 384.0
One to five years	1,201.9
Six to ten years	4.0
More than ten years	13.2
Marketable debt securities, Cost	1,603.1
Fair Value Maturities:
Within one year	381.8
One to five years	1,159.3
Six to ten years	3.9
More than ten years	12.0
Fair Value	$ 1,557.0

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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