Finance Receivables (Allowance For Credit Losses And Finance Receivables By Portfolio, Individually And Collectively Evaluated For Impairment) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 0	$ 0
Collectively evaluated for impairment	192,471	173,343
Total allowance for credit losses	192,471	173,343	$ 147,178	$ 127,364	$ 110,693
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	7,157,557	7,008,801
Total finance receivables	7,157,557	7,008,801	7,015,331	6,560,245	6,110,256
Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	186,254	166,810
Total allowance for credit losses	186,254	166,810	139,320	122,025
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	6,140,600	5,982,211
Total finance receivables	6,140,600	5,982,211	5,991,471	5,607,924	5,265,044
Wholesale
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	6,217	6,533
Total allowance for credit losses	6,217	6,533	7,858	5,339
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,016,957	1,026,590
Total finance receivables	$ 1,016,957	$ 1,026,590	$ 1,023,860	$ 952,321	$ 845,212