Commitments And Contingencies Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Other Commitments [Line Items]
Capital commitment	$ 10,000
Non-Exchange Traded Equity Investment in Mortgage Originator
Other Commitments [Line Items]
Guaranty Liabilities	125,000
Flow agreement March 2015 with mortgage originator [Member]
Other Commitments [Line Items]
Purchase commitment	200,000
Purchases made in connection with purchase commitments	99,200
Performance Guarantee [Member]
Other Commitments [Line Items]
Participation Interest in Repo Facility	10,000
Amount of Utilization	$ 173,500
Additional amount to be posted	5.00%
Financing Duration	6 months
Maximum Borrowings under Repo Facility	$ 200,000
Mortgage Loan Purchase Commitments [Member]
Other Commitments [Line Items]
Derivative notional	$ 20,601	[1],[2]

[1] Notional value represents principal balance of mortgage loan purchase commitments. Actual loan purchases are contingent upon successful loan closings in accordance with agreed-upon parameters.

[2] See Note 2 and Note 3 in Notes to Consolidated Financial Statements.