Quarterly report pursuant to Section 13 or 15(d)

Schedule of Available-for-sale Securities Reconciliation (Details)

v3.10.0.1
Schedule of Available-for-sale Securities Reconciliation (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face $ 28,376,636 $ 29,396,680
Unamortized Premium 1,269,603 1,370,959
Accretable Purchase Discount 689,263 700,671
Credit Reserve Purchase Discount 923,834 653,613
Amortized Cost 19,305,810 20,856,658
Unrealized Gain 578,137 544,198
Unrealized Loss 590,593 180,037
Available-for-sale securities, at fair value 19,293,354 21,220,819
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 18,556,622 20,023,621
Unamortized Premium 1,189,470 1,302,535
Accretable Purchase Discount 24,315 24,638
Credit Reserve Purchase Discount 0 0
Amortized Cost 16,344,079 18,359,746
Unrealized Gain 25,222 53,104
Unrealized Loss 580,310 174,125
Available-for-sale securities, at fair value 15,788,991 18,238,725
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 9,820,014 9,373,059
Unamortized Premium 80,133 68,424
Accretable Purchase Discount 664,948 676,033
Credit Reserve Purchase Discount 923,834 653,613
Amortized Cost 2,961,731 2,496,912
Unrealized Gain 552,915 491,094
Unrealized Loss 10,283 5,912
Available-for-sale securities, at fair value 3,504,363 2,982,094
Interest-Only-Strip [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 3,377,698 2,941,772
Unamortized Premium 229,293 223,289
Accretable Purchase Discount 0 0
Credit Reserve Purchase Discount 0 0
Amortized Cost 229,293 223,289
Unrealized Gain 15,728 10,955
Unrealized Loss 47,708 39,156
Available-for-sale securities, at fair value 197,313 195,088
Interest-Only-Strip [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 5,349,634 5,614,925
Unamortized Premium 73,708 65,667
Accretable Purchase Discount 0 0
Credit Reserve Purchase Discount 0 0
Amortized Cost 73,708 65,667
Unrealized Gain 3,843 2,163
Unrealized Loss 2,576 2,746
Available-for-sale securities, at fair value 74,975 65,084
Fixed Income Securities [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 15,178,924 17,081,849
Unamortized Premium 960,177 1,079,246
Accretable Purchase Discount 24,315 24,638
Credit Reserve Purchase Discount 0 0
Amortized Cost 16,114,786 18,136,457
Unrealized Gain 9,494 42,149
Unrealized Loss 532,602 134,969
Available-for-sale securities, at fair value 15,591,678 18,043,637
Fixed Income Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Debt Securities, Available-for-sale [Line Items]    
Principal/Current Face 4,470,380 3,758,134
Unamortized Premium 6,425 2,757
Accretable Purchase Discount 664,948 676,033
Credit Reserve Purchase Discount 923,834 653,613
Amortized Cost 2,888,023 2,431,245
Unrealized Gain 549,072 488,931
Unrealized Loss 7,707 3,166
Available-for-sale securities, at fair value $ 3,429,388 $ 2,917,010