Repurchase Agreements Counterparty Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Agreements
Repurchase Agreement Counterparty [Line Items]
Borrowings outstanding with counterparty	$ 292,859
Weighted Average Rate	3.19%
Equity at Risk	$ 43,698
Line of Credit Facility, Amount Outstanding	160,280
Line of Credit Facility, Maximum Borrowing Capacity	$ 400,000
Line of Credit Facility, Expiration Date	May 12, 2019
Line of Credit Facility, Interest Rate at Period End	3.38%
Number of Counterparties with Borrowings Outstanding | Agreements	17
Available Repurchase Agreement Counterparties | Agreements	36