Summary of Impaired Loans (Cash Basis Method) (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Financing Receivable, Impaired [Line Items]
Interest income recognized on a cash basis	$ 0.4	$ 0.5
Customer Retail \| Fleet
Financing Receivable, Impaired [Line Items]
Interest income recognized on a cash basis	0.3	$ 0.5
Customer Retail \| Owner/Operator
Financing Receivable, Impaired [Line Items]
Interest income recognized on a cash basis	$ 0.1

Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeCashBasisMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration