Loans, Notes and Certificates, and Loan Servicing Rights - Past Due Table (Details) - Loans at Fair Value $ in Thousands	Mar. 31, 2016 USD ($) Loan	Dec. 31, 2015 USD ($) Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Outstanding principal balance, past 90 days due	$ 28,398	$ 30,094
Outstanding principal balance, non-accrual loans	2,904	4,513
Net fair value adjustments, past 90 days due	(23,622)	(25,312)
Net fair value adjustments, non-accrual loans	(2,398)	(3,722)
Fair value, past 90 days due	4,776	4,782
Fair value, non-accrual loans	$ 506	$ 791
Number of loans, 90 days past due | Loan	2,440	2,606
Number of loans, non-accrual loans | Loan	282	382