Mortgage-Backed Securities - Gross Unrealized Losses (Details)	Dec. 31, 2021 USD ($) plantiff	Dec. 31, 2020 USD ($) plantiff
Investments [Line Items]
Allowance for credit loss	$ 0
Agency MBS
Investments [Line Items]
Fair value, Less than 12 Months	1,051,233,000	$ 19,266,000
Gross Unrealized Losses, Less than 12 Month	$ (20,118,000)	$ (399,000)
Number of Securities, Less than 12 Months \| plantiff	23	19
Fair value, 12 Months or Longer	$ 0	$ 749,000
Gross Unrealized Losses, 12 Months or Longer	$ 0	$ (133,000)
Number of Securities, 12 Months or Longer	0	2
Non-Agency MBS
Investments [Line Items]
Fair value, Less than 12 Months	$ 11,667,000	$ 33,417,000
Gross Unrealized Losses, Less than 12 Month	$ (247,000)	$ (408,000)
Number of Securities, Less than 12 Months	14	23
Fair value, 12 Months or Longer	$ 1,241,000	$ 2,156,000
Gross Unrealized Losses, 12 Months or Longer	$ (97,000)	$ (93,000)
Number of Securities, 12 Months or Longer \| plantiff	6	5

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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