Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Jun. 30, 2023 USD ($)
Amortized Cost Maturities:
Within one year	$ 440.9
One to five years	1,287.4
Six to ten years	1.3
More than ten years	12.5
Marketable debt securities, Cost	1,742.1
Fair Value Maturities:
Within one year	433.8
One to five years	1,241.6
Six to ten years	1.3
More than ten years	10.9
Fair Value	$ 1,687.6

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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