Annual report pursuant to Section 13 and 15(d)

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

v3.6.0.2
Available-for-Sale Securities, at Fair Value Schedule of Unrealized Loss on Investments (Details)
$ in Thousands
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Schedule of Available-for-sale Securities [Line Items]    
Available-for-Sale Securities, Number of Positions 1,239 1,181
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year 252 121
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year 125 182
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Percent Agency 95.80% 73.60%
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value $ 6,416,820 $ 1,503,939
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses (204,034) (26,984)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value 504,978 1,141,839
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses (39,955) (44,412)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value 6,921,798 2,645,778
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses (243,989) (71,396)
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value $ 6,147,713 $ 1,107,411