Reclassifications Out of Accumulated Other Comprehensive Income (Parenthetical) (Detail) (Truck, Parts and Other, USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plans, prior service costs, pre-tax expense	$ 0.9
Defined benefit pension plans, actuarial (loss), pre-tax expense	(31.7)
Cost of sales and revenues
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plans, prior service costs, pre-tax expense	0.8
Defined benefit pension plans, actuarial (loss), pre-tax expense	17.4
SG&A
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plans, prior service costs, pre-tax expense	0.1
Defined benefit pension plans, actuarial (loss), pre-tax expense	14.2
R&D
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit pension plans, actuarial (loss), pre-tax expense	$ 0.1