Secured Borrowings Secured Borrowings, Counterparty Information (Details) $ in Thousands	Sep. 30, 2016 USD ($) Agreements
Counterparty Information [Line Items]
Line of Credit Facility, Amount Outstanding	$ 287,538
Line of Credit Facility, Maximum Borrowing Capacity	$ 350,000
Line of Credit Facility, Interest Rate at Period End	1.39%
Number of Counterparties with Borrowings Outstanding | Agreements	18
Available Repurchase Agreement Counterparties | Agreements	32
Wells Fargo Bank, N. A. and affiliates
Counterparty Information [Line Items]
Repurchase Agreement Counterparty, Amount at Risk	$ 54,432
Borrowings outstanding with counterparty	$ 300,761
WAVG interest rate for amount outstanding with named counterparty	1.40%