Fair Value of Financial Instruments - Summary of Fair Value Estimates, Methods and Assumptions (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 112,835	$ 10,531	$ 4,023	$ 70,887
Receivables held for sale	171,466	82,503
Retail installment contracts held for investment, net	21,087,173	20,219,609
Unsecured Consumer Loans	1,000,545	954,189
Receivables from Dealers Held for Investment	108,200	94,745
Restricted cash	1,830,392	1,563,613
Notes payable — credit facilities	9,573,726	8,099,773
Balance	15,783,587	15,195,887
Estimated Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash and cash equivalents	112,835	10,531
Receivables held for sale	176,425	83,344
Retail installment contracts held for investment, net	21,644,945	21,465,236
Unsecured Consumer Loans	1,071,108	1,187,286
Receivables from Dealers Held for Investment	108,200	94,745
Restricted cash	1,830,392	1,563,613
Notes payable — credit facilities	9,573,726	8,099,773
Balance	$ 15,924,794	$ 15,565,013

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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