Finance Receivables (Finance Receivables) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	$ 7,411,816	$ 7,157,557	$ 7,008,801	$ 7,015,331	$ 6,560,245
Allowance for credit losses	(189,885)	(192,471)	(173,343)	(147,178)	(127,364)
Total finance receivables, net	7,221,931	6,965,086	6,835,458	6,868,153	6,432,881
United States
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	7,111,334
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	300,482
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	1,083,615	1,016,957	1,026,590	1,023,860	952,321
Allowance for credit losses	(7,787)	(6,217)	(6,533)	(7,858)
Wholesale | United States
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	1,007,956	939,621	961,150	965,379	903,380
Wholesale | Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	75,659	77,336	65,440	58,481	48,941
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	6,328,201	6,140,600	5,982,211	5,991,471	5,607,924
Allowance for credit losses	(182,098)	(186,254)	(166,810)	(139,320)
Retail | United States
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	6,103,378	5,901,002	5,769,410	5,803,071	5,398,006
Retail | Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, gross	$ 224,823	$ 239,598	$ 212,801	$ 188,400	$ 209,918