Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
Available-for-Sale Securities, at Fair Value Schedule of Unrealized Loss on Investments (Details)
$ in Thousands
Mar. 31, 2020
USD ($)
position
Dec. 31, 2019
USD ($)
position
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]    
Debt Securities, Available-for-sale, Number of Positions | position 875 1,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | position 20 122
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | position 18 151
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 251,134 $ 3,970,743
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (6,601) (25,061)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 16,364 735,727
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (817) (62,932)
Debt Securities, Available-for-sale, Unrealized Loss Position 267,498 4,706,470
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (7,418) (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 249,040 3,322,894
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (5,425) (6,645)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 16,057 524,739
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (807) (49,521)
Debt Securities, Available-for-sale, Unrealized Loss Position 265,097 3,847,633
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (6,232) (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 2,094 647,849
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss (1,176) (18,416)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 307 210,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (10) (13,411)
Debt Securities, Available-for-sale, Unrealized Loss Position 2,401 858,837
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss $ (1,186) $ (31,827)