Reclassifications Out of Accumulated Other Comprehensive Income (Parenthetical) (Detail) (Truck, Parts and Other, Reclassification out of Accumulated Other Comprehensive Income, Pension Plan, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	$ 0.3
Actuarial loss	4.9	10.5
Cost of sales and revenues
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	0.2	0.3
Actuarial loss	2.7	5.7
SG&A
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior service costs	0.1
Actuarial loss	$ 2.2	$ 4.8