Finance Receivables (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012
Finance Receivables
Number of finance receivable types	3
Finance Receivables
Gross receivables	$ 11,752,722,000	$ 12,011,387,000
Unearned finance charges and points and fees	(441,836,000)	(435,825,000)
Accrued finance charges	85,151,000	89,751,000
Deferred origination costs	31,624,000	31,551,000
Premiums, net of discounts	(195,000)	(137,000)
Net finance receivables	11,427,466,000	11,696,727,000
Carrying amount of consolidated long-term debt associated with securitizations	12,387,034,000	12,454,316,000
Finance receivables pledged as collateral for secured term loan	5,200,000,000	5,200,000,000
Unused credit lines	79,200,000	164,500,000
Consolidated VIEs
Finance Receivables
Net finance receivables	4,510,653,000	3,977,412,000
Carrying amount of consolidated long-term debt associated with securitizations	3,378,274,000	2,978,338,000
Personal Loans
Finance Receivables
Gross receivables	2,998,428,000	2,984,423,000
Unearned finance charges and points and fees	(416,533,000)	(402,828,000)
Accrued finance charges	34,974,000	36,937,000
Deferred origination costs	31,292,000	31,200,000
Net finance receivables	2,648,161,000	2,649,732,000
Personal Loans | Associated with securitizations
Finance Receivables
Net finance receivables	650,400,000
Retail Sales Finance
Finance Receivables
Gross receivables	189,804,000	233,300,000
Unearned finance charges and points and fees	(20,588,000)	(27,087,000)
Accrued finance charges	1,707,000	2,148,000
Premiums, net of discounts	(2,000)	(4,000)
Net finance receivables	170,921,000	208,357,000
Unused credit lines	0	56,300,000
Real Estate Loans
Finance Receivables
Gross receivables	8,564,490,000	8,793,664,000
Unearned finance charges and points and fees	(4,715,000)	(5,910,000)
Accrued finance charges	48,470,000	50,666,000
Deferred origination costs	332,000	351,000
Premiums, net of discounts	(193,000)	(133,000)
Net finance receivables	8,608,384,000	8,838,638,000
Real Estate Loans | Associated with securitizations
Finance Receivables
Net finance receivables	$ 3,900,000,000	$ 4,000,000,000
Maximum | Personal Loans
Finance Receivables
Original term	60 months
Maximum | Retail Sales Finance
Finance Receivables
Original term	60 months
Maximum | Real Estate Loans
Finance Receivables
Original term	360 months