Asset-Backed Financing - Assets And Liabilities Of Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 26, 2021	Dec. 31, 2020	Sep. 27, 2020	Apr. 30, 2020
Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount				$ 27,400
Finance receivables
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	$ 2,739,054	$ 2,704,750	$ 3,074,488
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(138,100)	(156,928)	(180,601)
Finance receivables | Asset-backed securitizations | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,362,454	2,129,372	2,422,841
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(119,975)	(124,627)	(143,775)
Finance receivables | Asset-backed U.S. commercial paper conduit facility | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	264,226	441,402	505,507
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(13,396)	(25,793)	(29,948)
Finance receivables | Asset-backed Canadian commercial paper conduit facility | Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	112,374	133,976	146,140
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(4,729)	(6,508)	(6,878)
Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	175,273	151,965	181,178
Restricted cash | Asset-backed securitizations | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	148,177	116,268	138,276
Restricted cash | Asset-backed U.S. commercial paper conduit facility | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	19,688	26,624	32,649
Restricted cash | Asset-backed Canadian commercial paper conduit facility | Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	7,408	9,073	10,253
Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,911	3,879	3,271
Other assets | Asset-backed securitizations | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,228	2,622	1,923
Other assets | Asset-backed U.S. commercial paper conduit facility | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	526	1,131	1,206
Other assets | Asset-backed Canadian commercial paper conduit facility | Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	157	126	142
Total assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,779,138	2,703,666	3,078,336
Total assets | Asset-backed securitizations | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,392,884	2,123,635	2,419,265
Total assets | Asset-backed U.S. commercial paper conduit facility | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	271,044	443,364	509,414
Total assets | Asset-backed Canadian commercial paper conduit facility | Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	115,210	136,667	149,657
Asset-backed debt, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	2,292,932	2,310,839	2,691,193
Asset-backed debt, net | Asset-backed securitizations | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	1,952,368	1,791,956	2,096,355
Asset-backed debt, net | Asset-backed U.S. commercial paper conduit facility | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	242,254	402,205	467,338
Asset-backed debt, net | Asset-backed Canadian commercial paper conduit facility | Unconsolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	$ 98,310	$ 116,678	$ 127,500