Contractual Maturities of Marketable Debt Securities (Detail) - Truck, Parts and Other - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Amortized Cost Maturities:
Within one year	$ 436.3
One to five years	981.3
Six to ten years	0.1
Amortized Cost	1,417.7	$ 1,445.3
Fair Value Maturities:
Within one year	436.8
One to five years	989.4
Six to ten years	0.1
Fair Value	$ 1,426.3	$ 1,448.1	[1]

[1] The December 31, 2015 consolidated balance sheet has been derived from audited financial statements.