Fair Values of Member Loans at Fair Value and Notes at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Member Loans at fair value	$ 1,237,468	$ 781,215
Notes and Certificates	1,242,668	785,316
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Member Loans at fair value	1,237,468	781,215
Notes and Certificates	$ 1,242,668	$ 785,316