Asset-Backed Financing - Assets And Liabilities Of Variable Interest Entities (Details) - USD ($) $ in Thousands	Jun. 28, 2020	Apr. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
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	$ 3,584,656		$ 1,592,333	$ 1,779,812
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(209,242)		(43,797)	(50,135)
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	2,780,217		826,047	1,106,973
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(166,635)		(24,935)	(32,426)
Finance receivables | Asset-backed U.S. commercial paper conduit facilities | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	584,153		533,587	500,895
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(34,938)		(16,076)	(14,651)
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	220,286		232,699	171,944
Transfers accounted for as secured borrowings, assets, allowance for credit losses, carrying amount	(7,669)		(2,786)	(3,058)
Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	210,949		71,498	89,260
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	161,257		36,037	52,593
Restricted cash | Asset-backed U.S. commercial paper conduit facilities | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	38,491		27,775	26,843
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	11,201		7,686	9,824
Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	2,572		2,716	1,805
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	1,235		778	277
Other assets | Asset-backed U.S. commercial paper conduit facilities | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	1,195		1,642	1,256
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	142		296	272
Total assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	3,588,935		1,622,750	1,820,742
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	2,776,074		837,927	1,127,417
Total assets | Asset-backed U.S. commercial paper conduit facilities | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, assets, carrying amount	588,901		546,928	514,343
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	223,960		237,895	178,982
Asset-backed debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	3,146,608		1,369,512	1,615,745
Asset-backed debt | 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	2,461,107		764,392	1,002,869
Asset-backed debt | Asset-backed U.S. commercial paper conduit facilities | Consolidated VIEs
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings
Transfers accounts for as secured borrowings, associated liabilities, carrying amount	540,840		490,427	464,136
Asset-backed debt | 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	$ 144,661		$ 114,693	$ 148,740