Balance Sheet Offsetting - Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Reverse repurchase agreements:
Net Amounts of Assets Presented in the Balance Sheet	$ 139,929	$ 118,262
Total
Gross Amounts of Recognized Assets	1,156,669	1,639,589
Gross Amounts Offset in the Balance Sheet		(1,773)
Net Amounts of Assets Presented in the Balance Sheet	1,156,669	1,637,816
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(1,097,025)	(1,564,596)
Net Amount	59,644	73,220
Institutional Counterparties
Securities borrowed:
Gross Amounts of Recognized Assets	1,013,025	1,518,372
Net Amounts of Assets Presented in the Balance Sheet	1,013,025	1,518,372
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(955,303)	(1,445,590)
Net Amount	57,722	72,782
Interest rate swaps | Institutional Counterparties
Derivatives:
Gross Amounts of Recognized Assets	836
Net Amounts of Assets Presented in the Balance Sheet	836
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(820)
Net Amounts of Assets Presented in the Balance Sheet	16
Credit default swaps | Institutional Counterparties
Derivatives:
Gross Amounts of Recognized Assets	2
Net Amounts of Assets Presented in the Balance Sheet	2
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(2)
Net Amounts of Assets Presented in the Balance Sheet	0
Reverse repurchase agreements | Institutional Counterparties
Reverse repurchase agreements:
Gross Amounts of Recognized Assets	139,929	118,262
Net Amounts of Assets Presented in the Balance Sheet	139,929	118,262
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(138,023)	(118,262)
Net Amount	1,906	0
Forward MBS Derivatives | Institutional Counterparties
Derivatives:
Gross Amounts of Recognized Assets	2,877	2,955
Gross Amounts Offset in the Balance Sheet		(1,773)
Net Amounts of Assets Presented in the Balance Sheet	2,877	1,182
Gross Amounts Not Offset in the Balance Sheet
Financial Instruments	(2,877)	(744)
Net Amounts of Assets Presented in the Balance Sheet	$ 0	$ 438