Mortgage-Backed Securities - Gross Unrealized Losses (Details)	Mar. 31, 2022 USD ($) plantiff	Dec. 31, 2021 USD ($) plantiff
Investments [Line Items]
Allowance for credit loss	$ 0	$ 0
Agency MBS
Investments [Line Items]
Fair value, Less than 12 Months	719,200,000	1,051,233,000
Gross Unrealized Losses, Less than 12 Month	$ (47,905,000)	$ (20,118,000)
Number of Securities, Less than 12 Months \| plantiff	53	23
Fair value, 12 Months or Longer	$ 425,586,000	$ 0
Gross Unrealized Losses, 12 Months or Longer	$ (41,409,000)	$ 0
Number of Securities, 12 Months or Longer	8	0
Non-Agency MBS
Investments [Line Items]
Fair value, Less than 12 Months	$ 61,333,000	$ 11,667,000
Gross Unrealized Losses, Less than 12 Month	$ (1,206,000)	$ (247,000)
Number of Securities, Less than 12 Months	51	14
Fair value, 12 Months or Longer	$ 962,000	$ 1,241,000
Gross Unrealized Losses, 12 Months or Longer	$ (106,000)	$ (97,000)
Number of Securities, 12 Months or Longer \| plantiff	5	6

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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