Quantitative Information about Significant Unobservable Inputs Used for Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified					6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Fair Value, Inputs, Level 3	Dec. 31, 2012 Fair Value, Inputs, Level 3	Jun. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value	Jun. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value Minimum	Jun. 30, 2013 Fair Value, Inputs, Level 3 Member Loans At Fair Value Maximum	Jun. 30, 2013 Fair Value, Inputs, Level 3 Notes And Certificates At Fair Value	Jun. 30, 2013 Fair Value, Inputs, Level 3 Notes And Certificates At Fair Value Minimum	Jun. 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	$ 1,237,468	$ 781,215	$ 1,237,468	$ 781,215
Notes & Certificates, Fair Value	$ 1,242,668	$ 785,316	$ 1,242,668	$ 785,316
Valuation Techniques					Discounted cash flow			Discounted cash flow
Discount rate						5.80%	14.50%		5.80%	14.50%
Net cumulative expected loss						2.10%	30.10%		2.10%	30.10%