Asset-Backed Financing (Assets And Liabilities Of Variable Interest Entities) (Detail) - USD ($) $ in Thousands	Sep. 24, 2017	Dec. 31, 2016	Sep. 25, 2016
Finance receivables
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	$ 949,253	$ 1,059,523	$ 1,174,508
Finance receivables | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	511,643	893,804	1,019,378
Finance receivables | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	298,197	0	0
Finance receivables | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	139,413	165,719	155,130
Allowance for credit losses
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	(27,591)	(29,041)	(31,091)
Allowance for credit losses | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	(15,798)	(25,468)	(27,847)
Allowance for credit losses | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	(9,233)	0	0
Allowance for credit losses | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	(2,560)	(3,573)	(3,244)
Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	63,380	67,147	79,661
Restricted cash | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	40,385	57,057	69,364
Restricted cash | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	14,922	0	0
Restricted cash | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	8,073	10,090	10,297
Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	2,790	3,207	3,394
Other assets | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	1,513	2,452	2,893
Other assets | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	927	329	150
Other assets | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	350	426	351
Total assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	987,832	1,100,836	1,226,472
Total assets | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	537,743	927,845	1,063,788
Total assets | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	304,813	329	150
Total assets | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, assets, carrying amount	145,276	172,662	162,534
Asset-backed debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	832,271	945,613	1,066,107
Asset-backed debt | Asset-backed securitizations | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	429,833	796,275	925,619
Asset-backed debt | Asset-backed U.S. commercial paper conduit facilities | SPEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	280,308	0	0
Asset-backed debt | Asset-backed Canadian commercial paper conduit facility | Variable Interest Entity, Not Primary Beneficiary
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	$ 122,130	$ 149,338	$ 140,488