Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Mar. 31, 2023 USD ($)
Amortized Cost Maturities:
Within one year	$ 472.9
One to five years	1,179.6
Six to ten years	1.8
More than ten years	27.3
Marketable debt securities, Cost	1,681.6
Fair Value Maturities:
Within one year	467.4
One to five years	1,142.5
Six to ten years	1.7
More than ten years	25.9
Fair Value	$ 1,637.5

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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