Loans, Notes and Certificates, and Loan Servicing Rights - Past Due Table (Details) (Loans at Fair Value, USD $) In Thousands, unless otherwise specified	Mar. 31, 2015 Loan	Dec. 31, 2014 Loan
Loans at Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Outstanding principal baalnce, past 90 days due	$ 20,202	$ 19,790
Outstanding principal balance, non-accrual loans	948	1,373
Net fair value adjustments, past 90 days due	(19,186)	(18,825)
Net fair value adjustments, non-accrual loans	(886)	(1,289)
Fair value, past 90 days due	1,016	965
Fair value, non-accrual loans	$ 62	$ 84
Number of loans, 90 days past due	1,869	1,797
Number of loans, non-accrual loans	95	125