Reclassifications Out of Accumulated Other Comprehensive Income (Parenthetical) (Detail) (Truck, Parts and Other, USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pension plans, Actuarial loss, pre- tax	$ 14.9	$ 31.7
Pension plans, Prior service costs, pre-tax	0.9	0.9
Cost of sales and revenues
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pension plans, Actuarial loss, pre- tax	8.4	17.4
Pension plans, Prior service costs, pre-tax	0.7	0.8
SG&A
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pension plans, Actuarial loss, pre- tax	6.5	14.2
Pension plans, Prior service costs, pre-tax	0.2	0.1
R&D
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pension plans, Actuarial loss, pre- tax		$ 0.1