Summary Of Significant Accounting Policies (Narrative) (Details)		12 Months Ended
		Dec. 31, 2016 USD ($) portfolio_segment	Dec. 31, 2015 USD ($)		Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of Portfolio Segments | portfolio_segment		2
Number of Reportable Segments | portfolio_segment		1
Monthly fee charged Dealer in Portfolio Program		$ 599
One-time enrollment fee in program		$ 9,850
Percentage of first accelerated Dealer Holdback payment retained		50.00%
Percentage of enrollment fee of first accelerated dealer holdback payment		50.00%
Period after Consumer Loan assignment that Dealer Loans written off		120 months
Period after month of purchase that Purchased Loans written off		120 months
Unamortized Debt Issuance Costs		$ 16,800,000	$ 16,800,000
Threshold to determine likelihood of being sustained		50.00%
Employer matching contribution, match percentage		100.00%
Matching contribution		1.00%
Employer matching contribution, additional match percentage		50.00%
Additional matching contribution		5.00%
Maximum matching contribution		3.50%
Recognized compensation expense		$ 3,600,000	3,100,000		$ 2,500,000
Advertising expense		300,000	300,000		$ 300,000
Cash and Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents		14,300,000	6,000,000
Restricted Cash And Cash Equivalents [Member]
Summary Of Significant Accounting Policies [Line Items]
Uninsured cash and cash equivalents		$ 224,100,000	165,100,000
Building [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P40Y
Building Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P10Y
Data Processing Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P3Y
Software [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P5Y
Office Furniture And Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P7Y
Leasehold Improvements [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P7Y
Software Development [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives		P5Y
Secured financings [Member]
Summary Of Significant Accounting Policies [Line Items]
Unamortized Debt Issuance Costs	[1]	$ 9,700,000	8,500,000	[2]
Senior Notes [Member]
Summary Of Significant Accounting Policies [Line Items]
Unamortized Debt Issuance Costs		$ 7,100,000	$ 8,300,000	[2]

[1] Warehouse facilities and Term ABS financings.

[2] Prior year amounts have been reclassified to reflect the adoption of ASU 2015-03, as amended by ASU No. 2015-15, which resulted in a reclassification of certain deferred debt issuance costs from other assets to secured financing and senior notes.