Finance Receivables (Investment Of Wholesale Finance Receivables By Internal And External Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	$ 7,157,557	$ 7,008,801	$ 7,015,331	$ 6,560,245	$ 6,110,256
Retail
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	6,140,600	5,982,211	5,991,471	5,607,924	5,265,044
Retail | Prime
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	4,966,193	4,768,420
Retail | Sub-prime
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	1,174,407	1,213,791
Wholesale
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	1,016,957	1,026,590	$ 1,023,860	$ 952,321	$ 845,212
Wholesale | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	688	1,333
Wholesale | Substandard
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	3,837	1,773
Wholesale | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	26,866	30,152
Wholesale | Medium Risk
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	9,917	14,620
Wholesale | Low Risk
Financing Receivable, Recorded Investment [Line Items]
Financing receivable, gross	$ 975,649	$ 978,712