Description Of Business (Percentage Of Consumer Loans Assigned Based On Unit and Dollar Volumes) (Details)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Portfolio Program [Member]
Description Of Business [Line Items]
Percentage of new consumer loans in unit volume		72.50%	78.60%	87.40%
Percentage of new consumer loans in dollar volume	[1]	68.50%	71.40%	82.80%
Purchase Program [Member]
Description Of Business [Line Items]
Percentage of new consumer loans in unit volume		27.50%	21.40%	12.60%
Percentage of new consumer loans in dollar volume	[1]	31.50%	28.60%	17.20%

[1] Represents advances paid to Dealers on Consumer Loans assigned under our Portfolio Program and one-time payments made to Dealers to purchase Consumer Loans assigned under our Purchase Program. Payments of Dealer Holdback (as defined below) and accelerated Dealer Holdback are not included.