Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other $ in Millions	Mar. 31, 2022 USD ($)
Amortized Cost Maturities:
Within one year	$ 432.7
One to five years	1,092.0
Six to ten years	5.7
More than ten years	13.9
Marketable debt securities, Cost	1,544.3
Fair Value Maturities:
Within one year	432.0
One to five years	1,057.9
Six to ten years	5.6
More than ten years	13.1
Fair Value	$ 1,508.6

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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