Loan Loss Allowance and Credit Quality - Summary of Defaults in Loan Modifications Accounted as TDRs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014 contract	Jun. 30, 2013 contract	Jun. 30, 2014 contract	Jun. 30, 2013 contract
Retail Installment Contracts
Financing Receivable Modifications [Line Items]
Troubled debt restructurings that subsequently defaulted	$ 70,811	$ 24,471	$ 120,275	$ 38,491
Number of contracts	7,234	2,609	13,123	4,234
Unsecured Consumer Loans
Financing Receivable Modifications [Line Items]
Troubled debt restructurings that subsequently defaulted		$ 0
Number of contracts		0