Annual report pursuant to Section 13 and 15(d)

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

v3.19.1
Available-for-Sale Securities, at Fair Value Schedule of Unrealized Loss on Investments (Details)
$ in Thousands
Dec. 31, 2018
USD ($)
position
Dec. 31, 2017
USD ($)
position
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Number of Positions | position 1,550 1,435
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions | position 290 253
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions | position 489 234
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 4,386,946 $ 12,198,870
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Percent Agency 71.10% 98.50%
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss $ (66,520) $ (65,313)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer 9,501,123 2,464,544
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss (370,082) (114,724)
Debt Securities, Available-for-sale, Unrealized Loss Position 13,888,069 14,663,414
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (436,602) (180,037)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months $ 3,100,000 $ 12,000,000