Derivative Instruments, Offsetting Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	$ 2,293,660	$ 1,602,589
Gross amounts offset in the consolidated balance sheet	(9,903)	(181)
Net amounts of liabilities presented in the consolidated balance sheet	2,283,757	1,602,408
Gross amounts not offset in the consolidated balance sheet in financial instruments	(2,235,043)	(1,594,910)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	(48,714)	(7,498)
Net amount	0	0
Repurchase Agreements [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	2,266,841	1,598,592
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of liabilities presented in the consolidated balance sheet	2,266,841	1,598,592
Gross amounts not offset in the consolidated balance sheet in financial instruments	(2,225,276)	(1,591,094)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	(41,565)	(7,498)
Net amount	0	0
Interest Rate Swaps [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	21,104	3,816
Gross amounts offset in the consolidated balance sheet	(6,455)	0
Net amounts of liabilities presented in the consolidated balance sheet	14,649	3,816
Gross amounts not offset in the consolidated balance sheet in financial instruments	(14,649)	(3,816)
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	0	0
Net amount	0	0
TBAs [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	4,064	181
Gross amounts offset in the consolidated balance sheet	(3,448)	(181)
Net amounts of liabilities presented in the consolidated balance sheet	616	0
Gross amounts not offset in the consolidated balance sheet in financial instruments	(616)	0
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 Liabilities [Abstract]
Gross amounts of recognized liabilities	1,651	0
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of liabilities presented in the consolidated balance sheet	1,651	0
Gross amounts not offset in the consolidated balance sheet in financial instruments	5,498	0
Gross amounts not offset in the consolidated balance sheet in cash collateral received (pledged)	(7,149)	0
Net amount	$ 0	$ 0

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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