Receivables (Summary Of Other Credit Quality Information Regarding Finance Segment Secured Loans) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total secured loans	$ 590,609,000	$ 675,109,000
Loans past due	62,570,000	90,508,000
Loans more than 90 days past due	56,087,000	158,000
Non-accrual loans	0	158,000
Impaired loans	0	0
Allowance for credit losses for impaired loans	0	0
Total allowance for credit losses - secured loans	2,778,000	1,270,000	$ 1,458,000
SFS
Segment Reporting Information [Line Items]
Impaired loans	0	0
Allowance for credit losses based on historical data	1,253,000	1,270,000
Total allowance for credit losses - secured loans	$ 1,253,000	$ 1,270,000	$ 1,458,000