Asset-Backed Financing (Narrative) (Detail)	1 Months Ended		3 Months Ended
	Dec. 31, 2017 USD ($)	Jun. 30, 2017 CAD ($)	Jun. 26, 2016 USD ($)	Apr. 01, 2018 USD ($)	Mar. 26, 2017 USD ($)
Variable Interest Entity [Line Items]
Company issued secured notes, net of discount and issuance costs	$ 5,714,527,000			$ 5,981,190,000	$ 6,017,858,000
Current unpaid balance - off-balance sheet retail motorcycle finance receivables	146,425,000			127,643,000	212,764,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Principal balance of finance receivable			$ 301,800,000
Gain on sale of finance receivable			9,300,000
Cash proceeds from sale of financial asset			$ 312,600,000
Secured Debt
Variable Interest Entity [Line Items]
Company issued secured notes, net of discount and issuance costs	806,860,000			724,266,000	$ 1,112,592,000
Secured Debt | Asset-Backed U.S. Commercial Paper Conduit Facility VIE [Member] | SPEs | U.S. Line of Credit
Variable Interest Entity [Line Items]
Line of credit, maximum borrowing capacity	$ 900,000,000
Debt instrument, term	5 years
Secured Debt | Asset-Backed U.S. Commercial Paper Conduit Facility VIE, Facility Two [Member] | SPEs | U.S. Line of Credit
Variable Interest Entity [Line Items]
Line of credit, maximum borrowing capacity	$ 300,000,000.0
Secured Debt | Asset-Backed U.S. Commercial Paper Conduit Facility VIE, Facility One [Member] | SPEs | U.S. Line of Credit
Variable Interest Entity [Line Items]
Line of credit, maximum borrowing capacity	$ 600,000,000.0
Secured Debt | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary | Foreign Line of Credit
Variable Interest Entity [Line Items]
Line of credit, maximum borrowing capacity		$ 220,000,000
Debt instrument, term		5 years
VIE, maximum loss exposure, amount				$ 32,700,000