Derivative Instruments, Offsetting Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	$ 24,439	$ 13,830
Gross amounts offset in the consolidated balance sheet	(181)	0
Net amounts of assets presented in the consolidated balance sheet	24,258	13,830
Gross amounts not offset in the consolidated balance sheet in financial instruments	(23,571)	(13,830)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	(687)	0
Net amount	0	0
Interest Rate Swaps [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	23,176	12,994
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	23,176	12,994
Gross amounts not offset in the consolidated balance sheet in financial instruments	(23,176)	(12,994)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
Swaptions [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	170	802
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	170	802
Gross amounts not offset in the consolidated balance sheet in financial instruments	(170)	(802)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
TBAs [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	349	34
Gross amounts offset in the consolidated balance sheet	(181)	0
Net amounts of assets presented in the consolidated balance sheet	168	34
Gross amounts not offset in the consolidated balance sheet in financial instruments	(168)	(34)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	$ 0
Treasury Futures [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets or liabilities	744
Gross amounts offset in the consolidated balance sheet	0
Net amounts of assets presented in the consolidated balance sheet	744
Gross amounts not offset in the consolidated balance sheet in financial instruments	(57)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	(687)
Net amount	$ 0

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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