TDRs Modified During Previous Twelve Months that Subsequently Defaulted (Detail) - Financial Services - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Modifications [Line Items]
Recorded Investment, subsequently defaulted	$ 0.4	$ 0.4
Customer Retail \| Fleet
Financing Receivable, Modifications [Line Items]
Recorded Investment, subsequently defaulted	$ 0.4	0.2
Customer Retail \| Owner/Operator
Financing Receivable, Modifications [Line Items]
Recorded Investment, subsequently defaulted		$ 0.2

Amount of investment related to financing receivables modified by troubled debt restructurings within the previous 12 months, for which there was a payment default.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953682-111524

Name:	us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration