Annual report pursuant to Section 13 and 15(d)

Available-for-Sale Securities, at Fair Value Schedule of Unrealized Loss on Investments (Details)

v3.20.4
Available-for-Sale Securities, at Fair Value Schedule of Unrealized Loss on Investments (Details)
$ in Thousands
Dec. 31, 2020
USD ($)
numberOfPositions
Dec. 31, 2019
USD ($)
numberOfPositions
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Debt Securities, Available-for-sale, Number of Positions | numberOfPositions 823 1,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | numberOfPositions 13 122
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | numberOfPositions 13 151
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 367,660 $ 3,970,743
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (1,705) (25,061)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 24,006 735,727
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (4,454) (62,932)
Debt Securities, Available-for-sale, Unrealized Loss Position 391,666 4,706,470
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (6,159) (87,993)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 367,660 3,322,894
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (1,705) (6,645)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 24,006 524,739
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (4,454) (49,521)
Debt Securities, Available-for-sale, Unrealized Loss Position 391,666 3,847,633
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (6,159) (56,166)
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months 0 647,849
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss 0 (18,416)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 0 210,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss 0 (13,411)
Debt Securities, Available-for-sale, Unrealized Loss Position 0 858,837
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss $ 0 $ (31,827)