Quantitative Information about Significant Unobservable Inputs Used for Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified					9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Fair Value, Inputs, Level 3	Dec. 31, 2012 Fair Value, Inputs, Level 3	Sep. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value	Sep. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value Minimum	Sep. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value Maximum	Sep. 30, 2013 Fair Value, Inputs, Level 3 Notes And Certificates At Fair Value	Sep. 30, 2013 Fair Value, Inputs, Level 3 Notes And Certificates At Fair Value Minimum	Sep. 30, 2013 Fair Value, Inputs, Level 3 Notes And Certificates At Fair Value Maximum
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Member Loans, Fair Value	$ 1,516,676	$ 781,215	$ 1,516,676	$ 781,215
Notes & Certificates, Fair Value	$ 1,522,975	$ 785,316	$ 1,522,975	$ 785,316
Valuation Techniques					Discounted cash flow			Discounted cash flow
Discount rate						5.50%	13.20%		5.50%	13.20%
Net cumulative expected loss						2.10%	29.30%		2.10%	29.30%