Derivative Instruments, Offsetting Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	$ 36,655	$ 24,439
Gross amounts offset in the consolidated balance sheet	(9,904)	(181)
Net amounts of assets presented in the consolidated balance sheet	26,751	24,258
Gross amounts not offset in the consolidated balance sheet in financial instruments	(26,751)	(23,571)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	(687)
Net amount	0	0
Interest Rate Swaps [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	33,200	23,176
Gross amounts offset in the consolidated balance sheet	(6,455)	0
Net amounts of assets presented in the consolidated balance sheet	26,745	23,176
Gross amounts not offset in the consolidated balance sheet in financial instruments	(26,745)	(23,176)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
Interest Rate Swaptions [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	6	170
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	6	170
Gross amounts not offset in the consolidated balance sheet in financial instruments	(6)	(170)
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	3,449	349
Gross amounts offset in the consolidated balance sheet	(3,449)	(181)
Net amounts of assets presented in the consolidated balance sheet	0	168
Gross amounts not offset in the consolidated balance sheet in financial instruments	0	(168)
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		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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