Location and Amount of Expense (Income) for the Cash Flow and Fair Value Hedges Recognized in Statement of Comprehensive Income (Detail) - Financial Services - (Gain)/loss on fair value hedges - Interest-Rate Contracts - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative [Line Items]
Derivatives	$ (0.8)	$ 0.8
Hedged term notes	1.4	(0.4)
Total income and expense	$ 0.6	$ 0.4