Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Dec. 31, 2021 USD ($)
Amortized Cost Maturities:
Within one year	$ 424.3
One to five years	1,099.7
Six to ten years	9.8
More than ten years	13.5
Marketable debt securities, Cost	1,547.3
Fair Value Maturities:
Within one year	425.6
One to five years	1,097.1
Six to ten years	9.7
More than ten years	13.3
Fair Value	$ 1,545.7

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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